Xfinity Mobile account issue

On 5/26/26 I called Xfinity customer service to address a billing issue for my account. we had a line that we had contacted Xfinity to disconnect and the line was still  connected we thought it was an error but we were still accruing charges for it with no service on the phone. I called Xfinity to see what was going on and after talking to customer surface representatives I was communicated to that my line should’ve been transferred when I moved to the new Xfinity Wi-Fi account address and the line was not disconnected properly and that I was told that I would be refunded the amount that I paid towards the line, because it should’ve been transferred and I was insured by Xfinity representatives that the amount that was on my account being charged for service would be removed. That has not happened and I’m being threatened with collections.