Billing Error/Fraud charge Xfinity Mobile

Purchased a new iPhone and paid in full. It took a month to arrive, charges verified on credit card. The following month I was charged $50 for a phone payment. After an exhaustive chat message (which I saved the transcript) I was credited $50 and the commitment was made to ensure the problem was fixed. I indicated a healthy skepticism. Sure enough, my credit card was charged and additional $50 for last month and I see the plan to charge $50 next month. I believe the term is "Fraudulent Charge" when a company is informed they incorrectly billed you, when they repeat it. 1. How do I stop the charge; 2. How do I get a refund to my card, now; I plan to put a fraud hold on my cc Monday morning, and will be contacting the BBB. Not sure what else I can do to stop you from cheating this customer.