the link he provides is for wireline complaints. Wireline means hardwired phone lines like you have at home (no insult meant in the explanation, many people don't know that), it has nothing to do with wireless complaints and he continues to post it for that purpose.

Yes, it is for valid cable complaints and, if they charged this OP twice, once when she cancelled and then again with an auto pay, then they are wrong. If they simply took the final bill out of her checking account, they are not wrong. It's something you agree to when you sign up for auto pay. That's another reason I don't use that type of service.

Typically when you cancel a service that is billed on a prorated basis, you end up getting two final bills, one as a final bill and then another which credits any prorated services that were paid for and not used.
When I cancel any wireless services for my clients, I never process the invoice that comes in soon after cancelling because I know that I'll get another with a credit. I wait for that one so I don't have to pursue a refund if I overpay. It is notoriously difficult to get a refund check from any of these companies, telecom, wireless or cable, after your account is closed.