Not receiving credit for phones traded in phones

I have contacted Xfinity Customer Service every month since July 2025 because the credit for the two phones we traded in weren't showing up. Every month they assure me it's fixed and every month I end up calling in again. I've had it!!!!!  Xfinity is breaching the agreement we signed with them, and they are legally obligated to make this right. I am so tired of calling in and talking to different people who just give me the same speech and then nothing ever gets fixed!!  I'm ready to pay off my phones and go elsewhere.  If Xfinity can't get their billing right after all these months, then I have no confidence in them anymore.  

Anybody ever tried going to an xfinity store to take care of a billing issue?  At least maybe then I could talk to someone who won't transfer me to 3 different people!!  Last time I was on the phone with them for over an hour - that was time I didn't have to be [Edited: "Language"] around with incompetent people who couldn't do anything to help me