I recently booked a cruise through and paid the full amount by credit card. When the information packet arrived with our tickets, I was surprised to find a notice that we had reserved a special senior-citizen rate, with a warning that if we couldn't prove our age when we checked in, we would be charged extra.

We never told anyone we were seniors - in fact, the birthdays we gave when we bought the cruise clearly indicated that we aren't senior citizens.

When I called, an agent said she would ask our cruise line to look into the matter. Now I'm being told that we owe $250 on top of the $1,133 we've already paid.

After almost a month of calling, our agent said she couldn't get the fee waived and asked if we wanted to cancel the cruise. What should I do?

- B.D., Conroe, Texas

Answer: I think you should go on your cruise without paying another penny.

There are times when the price of a cruise can change even after you've bought your tickets. A few years ago, when fuel prices suddenly spiked, some cruise lines retroactively added a fuel surcharge to their cruise fares. But this isn't one of those times.

Somehow, you bought a senior fare even though you aren't old enough to qualify for one.

If your transaction had been done online, through the Web site, then this would probably be an open-and-shut case. Most travel sites have the capability of showing screen shots that prove you pushed the button that resulted in your itinerary. But you made your reservation by phone.

When you run into a problem with a phone reservation - and it basically becomes your word against someone else's - it's important to switch to a medium that allows you to create a paper trail. E-mail or even a regular letter will do the trick. Having a formal record of your request to fix this problem, and the company's response, is critical should the case ever get escalated to a supervisor or become a credit-card dispute or even an action in small-claims court.

Repeated phone calls to your online travel agent are less helpful. Although many companies record their calls, there's no transcript that you can get easily. You need something in writing.

I asked to look into your reservation. It turns out the company erroneously sold you a senior rate, and after you discovered the mistake, it called your cruise line in the hopes that it would honor the lower fare. When it wouldn't, you were given the option of paying an extra $250 or canceling your cruise.

An representative contacted you, apologized for the misunderstanding and offered to pay the difference in your cruise fare.