I have been charged for the full amount of a phone that I don't have

Hello, I have been on numerous calls with xfinity mobile support and I finally got in touch with a so called manager who went by the name of Karim and told me his operator ID was AE81.  First of all, I have been with Xfinity home for over 10 years and the customer service that he provided was below sub par, not even apologizing for the issue that I have.  Back in 2023, I had thought about switching from Verizon to Xfinity mobile but lucky I didn't because the customer service seems to be non existent.  In any case, I returned all the devices without even activating them, seems like one of them either got lost on return or something else, the IMEI for the the iphone 15 pro was never activated and I believe that they said that IMEI was not active.  Since I have xfinity home, I never really paid much attention to the fact that I was being charged for that device every month for 2 years! When I finally realized it, the last payment was coming out of my account!  Someone at Xfinity has to be able to help as this is straight up robbery and not a bit of sympathy for your good clients.  Hopefully, this post won't fall on deaf ears. Someone should pay attention to Karim AE81, I don't think he likes his job or Xfinity clients.