Repeated billing after account should have been canceled

I have contacted Xfinity multiple times about an unresolved billing and cancellation issue.
A new Xfinity account at the same address started service on August 14, 2026 and has already been billed and paid, but my old account continued to be charged.
I received a cancellation confirmation on September 21, but the “Last day of service” is blank, and my old account still shows an upcoming automatic payment.
I need Xfinity to verify the effective disconnect date and correct/refund the charges after August 14.