I overlooked that one, thanks for the link.
With many businesses where a bookkeeper (or the accounts payable department) just pays all bills with no questions asked, this could happen and nobody at the company would know about it. I know for a fact (I have run into this with multiple clients) that if you have a web hosting account, or an ISP account with them that is billed through the telephone bill, or done using autopay with a credit card, it is a common practice for them to continue collecting the monthly fees long after the account was migrated to another provider (this will continue indefinitely, or until the credit card expires).
With AT&T, nothing surprises me anymore. Their "Rethink Possible" mantra is quite apropos for their business practices.--
History does not long entrust the care of freedom to the weak or the timid.
-- Dwight D. Eisenhower