Cancelled Contract/Account is not cancelled after three months and now I have collections started.

Good day!
I have terminated my contract and returned equipment to a one of local shops in Antelope, California in June 2025. But after that I get messages that my services aren't paid, despiteds the fact that I don't use Xfinity anymore, moreover, I don't reside at account address, and moreover, I'm not in US anymore since July 14, 2025. I have contacted Xfinity Support in August, they said things are solved, but... now, for couple a days since the end of Septermber I started getting emails from collectort on my debt to Xfinity.

To send a message to any direct mail in Xfinity Support - I couldn't find it. The cancellation service now foresees a phonecall, would they call me internationally? I doubt. So, I have to renew my US phone number to speak about three-months done deal, just to prove what? That I don't/can't use Xfinity physically being out of country and officially terminated my contract? Because someone couldn't close my account internally and I have to face all these difficulties? I guess, after several months of such an experience there is still noone interested in solving this issue.

Prove me I'm wrong, please.