Ongoing billing issues

I was an Xfinity mobile customer for a short time. When we signed up we got talked into buying 2 iPads. We very quickly discovered that over service was very poor at our home, which was supposedly checked when we were signing up. We spent days talking with agents because our phone service was intermittent and the iPads rarely worked. After a short time and because an agent acknowledged that our service was not going to improve any time soon we requested and we’re told we could send the iPads back. We did so immediately and thought that would be the end of it. In April of this year we discontinued our phone service finally because it was so bad. Since then we have continued to have charges every month. I have called repeatedly to discuss changes and have received multiple explanations and promises of refund. Today I spent literally 4 hours on the phone with Xfinity and spoke to several different “supervisors” and got several different stories. I was finally told by a supervisor that we are still paying off the iPads and have been since day one. When I explained that we sent the iPads back last year within a month or so we f purchasing he said that they had to be returned within 14 days of accepting them. I explained again that your company agreed to take them back due to Xfinity being unable to provide adequate service at our home. We were never informed that we would still have to pay for them and didn’t realize that we were because the bill is not itemized.Why in the world would we agree to that??? Then the same man said we only returned one after already acknowledging that they  both had been returned well over a year ago. I would really appreciate speaking to an actual supervisor to assist in ending this ridiculous money grab.