Xfinity customers in Philadelphia and the Pennsylvania suburbs have had to deal with Comcast Corp.'s conversion to a new billing system along with the recent outage of the X1 set-top box.

Comcast officials say the two events - the billing-system conversion for hundreds of thousands of Xfinity customers and the X1 foul-up for a limited number of Xfinity customers - are separate, but they overlapped in parts of the Philadelphia area. Most of the problems are over, the company says.

Comcast now plans to extend the billing-system conversion to New Jersey. The tentative date for the New Jersey conversion is Dec. 8, Comcast spokesman Jeff Alexander said Tuesday.

Comcast is the largest cable-TV provider in New Jersey, with systems throughout the state.

Comcast converted billing systems in Bucks, Chester, Delaware, and Montgomery Counties and Philadelphia on Nov. 2.

CSG Systems International Inc., of Englewood, Colo., disclosed in July that it had expanded its billing-services relationship with Comcast. CSG also provides billing services to Time Warner Cable Inc. Comcast is seeking to acquire Time Warner Cable in a $45 billion deal.

Comcast believes that the CSG system will make the monthly bills more transparent with itemized charges, and will improve communications inside Comcast, making technician calls more efficient.

Xfinity customers get new account numbers with the CSG conversion and will have to update banks to continue auto-payment options.

"We know it may not have been seamless for some customers recently, and want them to know the majority of the work is behind us," Alexander said, "and we truly appreciate their patience."

Comcast will boost staffing for the New Jersey conversion and benefit from the lessons learned in the Philadelphia-area conversion, Alexander said.

Comcast told subscribers in early November that it would credit customer accounts related to the multistate X1 outage. There are five million X1 set-top boxes installed in Xfinity homes nationwide, and not all of them went down.

Company officials said Tuesday that they had identified the X1 customers who lost service and that those customers were informed by late last week in e-mails that they would have their accounts credited $20 within the next month. Comcast has not said how many customers would get the credit.