help from someone who actually can delete a bill that is NOT owed

In July 2024, Xfinity said the only way to remedy an issue I was having was to combine a tv account and separate internet account. After much ado and wasting too much time, I did that. They kept my tv account as my account (with the added internet) and said they would cancel my then existing internet account. They did not do that. I am still getting a bill for the old separate internet account. After a LONG ordeal of being transferred and chatting and talking to people, I was guaranteed it was taken care of. IT WAS NOT! Beyond being maddening to be told this has been taken care of, albeit, months late, If this mistake on Xfinity's end is on my credit report, it is extra aggravating. What will Xfinity do to remedy this. I do not want to waste hours more on the phone or chat with this. The level 1 people say they can do it, but obviously they cannot.