Your airline lost your luggage. Your car-rental company ran out of sedans and handed you the keys to a gas-guzzling van. Your hotel can't find your reservation, and you're homeless on vacation. What now?

I've been mediating travel disputes my entire career, and I know what to do. I'm National Geographic Traveler's ombudsman, and I write the "Travel Troubleshooter" column that appears in this section every week. When vacations head south, I get the call.

Over the years, I've developed a few insider tricks for fixing a derailed trip: whom to write, what to say, and where to go when no one listens. But if I had to distill everything into one simple rule, it would be: The sooner you speak up, the better your chances of getting what you deserve.

But I'm getting ahead of myself. Here are my strategies for making things right when they have gone wrong:

Don't wait. Instead of writing a letter or calling when you get home, mention your problem before you check out, deplane or disembark. The person behind the counter frequently is empowered to fix the problem on the spot. Leave without saying anything, and you'll have to deal with an outsourced call center whose operators have 50 ways (or more) to say no.

Keep meticulous records. When you're having the vacation from hell, record-keeping is critically important. Take snapshots of the bedbug-ridden hotel room or the rental car with a chipped windshield. Keep all e-mails, brochures, tickets and receipts. In extreme cases, I've seen travelers print computer screen-shots of their reservation to prove they made it.

Take a deep breath. Stay calm. Even though you may feel like ranting about your trip, resist the temptation. You're going to need to stay focused to get what you want from the company. If you need to, take a few hours before sitting down in front of a typewriter or computer to compose a letter. A levelheaded letter is far likelier to get results than a threatening one.

Talk is cheap. Picking up the phone may seem like the easiest way to register disapproval with a travel company. For immediate gratification, there's nothing like chewing someone out by phone. In fact, though, the phone can be problematic because no usable paper trail is created. (Although many companies record call-center conversations, you won't have access to those tapes.) It's better to do everything in writing.

Write tight and polite. The most effective e-mails and letters are very short - no more than one page, or about 500 words. They include all details necessary to track your reservation, such as confirmation numbers and travel dates. They're polite, dispassionate, and free of spelling errors. There's a real person on the other end reading the e-mail or letter, so something as seemingly insignificant as bad grammar can determine whether your complaint is taken seriously or routed to the circular file.

Start at the bottom. If you come back from your vacation and need to contact a travel company, go through channels. Give the system a chance to work. It may. Then again, it may not. Start by contacting the company through its customer-service department. The point of this exercise is to collect evidence that you gave the company a chance to make things right. That could be important later, if the company tries to blow you off and you need to go to court.

Cite the rules. Your complaint has the best chance of a satisfactory resolution if you can convince the company that it broke the law or didn't follow its own rules. Airlines have what is called a contract of carriage: the legal agreement between you and the company. Cruise lines have ticket contracts. Car-rental companies have rental agreements, and hotels are subject to state lodging laws. You can ask the company for a copy of the contract or find it on its Web site.

Tell them what you want nicely. I've already mentioned the importance of a positive attitude. I'll say it again: Be extra nice. The two most common mistakes that people make with a written grievance are being vague about the compensation they expect and being unpleasant. Also, make sure that you're asking for appropriate compensation. I've never seen an airline offer a first-class, round-trip ticket because flight attendants ran out of chicken entrees.

Copy all the right people. Yes, customer-service representatives review the list of everyone you copied on an e-mail or letter. When they see you've shared a grievance with a few other folks, it will give the complaint more weight. The people you copy will depend on the type of grievance. Just think of it as the exclamation point at the end of your letter.

Press "send" or mail. E-mail is an acceptable way to file a grievance. A few things to keep in mind: If you use a Web-based form, keep a copy of the letter (don't just type directly into the form and hit "send" because you won't have a copy). Make sure your subject line describes the grievance. "Flight 123 query from passenger Jones" is preferable to "I'LL NEVER FLY ON YOUR AIRLINE AGAIN." If you need a return receipt, snail mail still works best.

Be patient. The typical grievance takes six to eight weeks to resolve. Yes, six to eight weeks. A lot of them take less time, but many routinely test the eight-week limit. There's no excuse for dragging things out, of course, but patience is a must when dealing with travel companies.

Turned down? Get it in writing. Don't accept "no" for an answer by phone. Ask the company to put it in an e-mail or letter. That way, you have something to add to your file. I hope you won't be rejected, but if you are, you want cold, hard proof that the company gave you a thumbs-down. No worries - you're not out of options.

Appeal your case. Did you get a form letter politely asking you to take a hike? It's not over. Every travel company has a vice president of customer service or a manager who is in charge of dealing with passengers or guests. That's who you need to contact next. These executives go to great lengths to keep their names and contact information from becoming public, but a quick online search will reveal the information. I list many of them on my Web site (www.csr.elliott.org).

Take another deep breath. Don't overreact. Simply enclose copies of all of the correspondence, with a cover letter to the vice president politely asking the company to reconsider its decision. Copy the same group of people. Be pleasant, non-threatening, but firm.

Take extreme measures. If the company still says no, you should consider the "Hail Mary" - a respectful but insistent letter overnighted directly to the chief executive officer, along with the rejections you've received. This is a little-known loophole in the system. Something FedExed to the top executive has an excellent chance of being read by that person. Another last-ditch option: Consider disputing the charge on your credit card.

Go to court. Most travel-related issues would be handled by a small claims court, which doesn't require that you hire a lawyer. Travel companies like going to court about as much as the typical person does, so filing a complaint may be enough to get the airline, car-rental company or hotel to see things your way.

Cut your losses. Sometimes, the cost of pursuing a complaint, in time and money, outweighs the benefits. Going after a travel company for nothing more than an apology may not be the most productive thing to do. Pick your battles.

Troubleshooting a trip isn't difficult. With the right information, a positive attitude, realistic expectations and, above all, patience, you can resolve 99 percent of all travel grievances. The other 1 percent? That's my department.

Copy Those Complaints

It's not just who gets your letter that matters - it's who else gets it. Here's a rundown of whom to copy.

Airlines

Aviation Consumer Protection Division, C-75

U.S. Department of Transportation

400 Seventh St., S.W.

Washington, D.C. 20590

Car rentals

Send copies to the state attorney general in the state where you rented the car (not your home state) and, if it involves a questionable insurance claim, that state's insurance commissioner.

A list of attorneys general is available on the National Association of Attorneys General Web site at www.naag.org/ag/full_ag_table.php.

A list of state insurance commissioners can be downloaded at www.naic.org/documents/members_membershiplist.pdf.

Hotels

If your complaint is about a hotel, you can also copy the attorney general in the state where the hotel is located.

Travel agents

Many agents are members of the American Society of Travel Agents, which will investigate ethics complaints.

American Society

of Travel Agents

1101 King St., Suite 200

Alexandria, Va. 22314

Web site: http://astanet.com

If you feel you're the victim of an agent's bait-and-switch or some other form of dishonest advertising, send a copy to:

Federal Trade Commission CRC-240

Washington, D.C. 20580

Web site: http://ftc.gov

Cruises

Federal Maritime Commission

800 N. Capitol St., N.W.

Washington, D.C. 20573

If your complaint involves a sanitation issue, send a copy to:

Centers for Disease Control and Prevention

1600 Clifton Rd.

Atlanta, Ga. 30333

Appeals

If you get a "no" after your first round of letters, don't worry. During your appeal, here are two more people to copy.

Your family lawyer.

Me. You can e-mail me at celliott@ngs.org.

- Chris ElliottEndText

Christopher Elliott is the ombudsman for National Geographic Traveler magazine. E-mail him at celliott@ngs.org, or troubleshoot your trip through his Web site, www.csr.elliott.org.