In some states, the Public Utilities Commission will nail them to a cross for that. Not because they care about consumers, but because they get off on screwing over telecoms.
Had a cell phone waaay back with AT&T Wireless (which was a completely different company than the one that uses the name now). They moved their payment processing center from Los Angeles to Arizona, and didn't update the computer than printed the statements to have the new mailing address on the payment stub (yeah, that long ago). Six months later, the forwarding address expired, and I got a payment back as undeliverable, and they suspended the account for non-payment.
When the California PUC got done with them, I got three months of free service, which was just enough time to get off my ass and move the phone number to another carrier.