Re buy out complaint

I know Xfinity value their customer service that is one of the reasons why when I was offered to switch I did. Then when I received a $2500 bill from my previous provider I knew something was not right. Try to go one of the retail locations. One of the reps told me that the transfer that was done was never done right. She send me back to customer service on the phone. Did that they send me right back to the store. So I have been going back and forth for a month now trying to resolve this issue in the mean while I’m still sitting with a $2500 bill.