Unable to Cancel Landline after several attempts

I’ve not only chatted, but called Xfinity to cancel my landline. Spent several hours going back and forth before finally being assured it will be taken care of. I even requested an email confirmation of the changes, but the agent said “it will take a few billing cycles.” I waited a few, chatted back in, and was told the same thing. Do I need to file a report to the FTC to get this resolved? Nobody at Xfinity is pushing my request through. I end up in an endless loop of calling in or chatting.