I cancelled my now mobile and still been charged

We moved to another provider in December 23th, and Xfinity keep charging my card for my line and my husbands. NOBODY CAN SOLVE THE PROBLEM. I’ve been in Xfinity store 4 times, called at least 8 times and they are always addressing each other the solution but nobody do it. We can’t even access online bc we ar e o longer with Xfinity now mobile.
I’ve been paying for months and I can’t get my money back or made this payments stop. I’m really considering sue the company for that