Cancelled Xfinity NOW services yet being charged for next month

I discontinued my NOW services on May 12, 2026 and received a cancellation confirmation email the next day. However, I was just charged for June via autopay. And I have proof of both mails - 1) Cancellation of services 2) Yet being charged for that service for next month I.e. June 
When I log into my regular Xfinity account, it shows no active service and no chosen payment method shown. I guess my credit card details are stored and used even after I cancelled my services. I have already spent hours being transferred in circles between agents who claim they cannot help with NOW accounts.
Xfinity NOW customer service: What are you going to do to resolve this erroneous charge, and when will my refund be processed?