How do you get a phone removed?

We have been Comcast customers since 2005.  We have had 3 landlines through Xfinity triple play… one phone comes as part of the triple play bundle plus an additional 2 phones for which we are paying $10 each.  One landline belonged to my mother.  She passed away (at 98 years old) on January 10th.  I called 2 days later and got a customer service rep who said he could take care of the problem, and gave us the amount of the new bill.  He said the phone would be removed from our account within 24 hours.  

A week later, the phone was still ringing.  So I called customer service two more times, but was given the same original amount of the bill.  Both agents assured me that they could take care of the problem… but it didn’t happen.  Finally I went to an official local Xfinity store—with great difficulty as I‘ve had a stroke, and must wait for someone to take me.  They couldn’t relê it, but said they could finish it the next day.  They said they would call.  Two days later now… haven’t called.  Phone still ringing.

The due date for my bill was yesterday, so I deducted $10, and payed it.  But there is no way to dispute a Comcast bill.

Any suggestions on what to do?  I‘m on the cusp of completely dropping Comcast and going with CenturyLink.