Terminated account with Xfinity back in March, also being charged for equipment returned back in 2019, and at the wrong address...

The account was terminated (and rightly so) around the beginning of March this year. A fee was tacked on and a bill was received for that charge. The person we spoke to on the phone did not disclose this to me at the time of calling to terminate. Secondly, a new bill was received on April 3rd stating that there was equipment needing to be returned. This is incorrect - due to the fact that Xfinity's modem was sent back to them through UPS on Tuesday, February 26, 2019 at 10:24 AM. The location is UPS CC, Baltimore, MD, 21205-3513, 6501 Quad Avenue according to the receipt that I kept all of these years as future evidence for when I knew this would happen. I am more than fed up with dealing with you people, and if this is not resolved I will be pursuing higher channels of action. Thirdly, the account number is tied to my original address in Baltimore. I have since moved to a new address in Edgewood, and was unable to change the address in the space of over a year due to Xfinity's website being completely unusable, broken and poorly maintained. I will be expecting a response before the day is over. If not, I will be making phone calls to higher-ups. Have a nice day...