Billed with late fee after canceling service

I cancelled my Xfinity service after confirming Xfinity would not be available at my new house. The cancellation took effect as of 8/9/2024.

Today, I received a bill for 2 billing periods (July 21 through August 20, and August 21 through September 20), with a $10 late fee applied.

This kind of makes sense: my usual auto-pay for the 7/21 through 8/20 would have been applied to my account on 8/11, but the auto-pay didn't take place because I'd already cancelled my account.

However, at the time of cancellation (i.e., before my bill was due on 8/11), I was told I'd receive a final, prorated paper billl, so I did not know that I still needed to make sure the usual payment went through.

Is it please possible to check on whether I need to pay this entire bill? And to remove the late fee, since this contradicts what I was told about receiving a final paper bill?

Thank you!