Help! Billing nightmare!

I ended my Internet and mobile phone service with Xfinity in September of 2025, and EVERY MONTH SINCE I have had a payment taken off of my credit card! Every month a different amount, from like $12 to $130 has been charged to my credit card. Every time I call, the representative says I don't owe anything, they reverse the charge, and promise it won't happen again. Then every month a new charge!