Closed wrong account - issues returning modem

One of the agents closed the wrong account for my wifi after I had moved to a different state. The link that was sent to me was for a device I havnt had in well over 6 years, and had already been replaced via upgrade. So I  have a serial number that does not match the device I have. Called customer service and they said there was nothing they could do. I'd have to go into an xfinity/ Comcast store and go through the whole ordeal with them in person. This is absolutely ridiculous! The closest store to me is close to an hour away from me, and I dont have the ability to get there during the week. Saturday is my only available day to be able to do this. It's all really frustrating because I'm not the one who [Edited: "Language"] up... an xfinity agent [Edited: "Language"] up and now im having to pay for it. [Edited: "Language/Inflammatory"]