Erroneous bill

I recently moved and the new tenants put in a service cancellation so they could start an account. I received an email from Comcast confirming that request and stating clearly that my last day of service would be August 24, 2020. I got an ebill on Aug 31 for Sep 6 -Oct 6, so I called and was told that this was just automated, not applicable, and confirmed in the system that my last day of service was indeed Aug 24.

Yesterday I got an email that my automatic payment for that bill of $37.96 was still going ahead, so I called in today. The customer service agent was very unhelpful and insisted that since services were not disconnected until Sep 8, I would be charged $2ish dollars for those days. I have a confirmation email that says "Last day of service:   Monday, August 24, 2020", so I really don't understand why I am being charged for services beyond that date.