Canceled service, still getting billed.

Last month I had make a freaking appointment just to cancel my internet service, and then put up with an aggravating, demanding rep who kept wanting to persuade me not to cancel. Eventually I was told that service would be canceled as of Sept 21. Yesterday I got an email saying my bill is overdue. It is impossible to contact this company by email or message, phone wait times are upwards of 30 minutes, and I no longer live in the United States so these are international calls for me. Xfinity is an awful company with no respect for its customers, and too incompetent to even successfully cancel service. I will never, ever do business with them again and will tell everyone I know to do the same.