Internet tv home billing fraud billing issue

Xfinity lately are really bad their billing system on the app acting weird. We got charge extra on our normal bill. They charge us twice on month of December with the amount of $236 our normal bill and another $399 so  we only dispute the $399 but they decided to refund both the bad thing is the system is not showing our card that we only use for xfinity auto payment for the amount of $236 the system showing different payment from checking account ending 1941 which we never have. How can that happen that the card we use for auto pay ending 3710 is recorded on their system that 1941 paid for the amount of $236 that’s why they refund the wrong person because that’s how their system showing. So for short we never get the money back the amount of $236. So it’s look like we skip the December payment now bcoz they refund it but not to us I don’t know who own that 1941 . So for the month of January we ended up paying almost $500 for that fraud happen on my xfinity app account. How how that can happen that on my statement my card got charge of $236 but your system showing that $236 got paid by someone or different card ending 1941 he/she got lucky to get my refund supposedly tsk. very disappointed that’s why I ended up cancel my service because even the representative in xfinity store they didn’t do any thing to help our issue they just told us you gotta pay what you gotta need to pay very rude for I’m premium user but no one can solve our concern with that kind of weirdest happen to our billing in the system. So my last day for my service is until January 16 today is January system I already return everything to the store the representative there keep saying it’s all cancel but it’s still showing balance of $257 that due to Feb 8 lol. What’s that billing us even we already request tha cancellation last January 4 we just wait our last day of cycle yesterday jan 16 2025  so we can return the equipment today jan 17 2025. The representative of xfinity store by comcast in 176st puyallap is not helpful at all I drove 3x in their store because they didn’t mention what all the equipment do I need to return for them. They told me to return this and that why they cannot told me one time only what all we need to bring cause us more fuel