In the end, they couldn't get me hooked back up, apparently because the username and password database is so complex that it takes weeks to enter a pair of values in it.
Well, today I received a letter from them which was forwarded from the old address:
I would like to thank you for your patience and understanding while we worked to resolve your recent concern.
At AT&T California, we pride ourselves on consistently delivering exceptional service to every customer. Unfortunately, in this case we failed to meet our commitment and your expectation of us.
Now that we have addressed your concern, I hope we also have been successful in restoring your confidence in us.
We want you to know that we appreciate your business. We look forward to meeting your telecommunications needs and providing you with outstanding customer service for many years to come.
AT&T California values your business and looks forward to serving you again. If you have any questions or concerns, please contact us at 1-800-310-2355.
(large blank unsigned space)
I can honestly say that, pursuant to this letter, my feelings about AT&T California service have never been stronger. In fact, I feel they're quite exceptional. At least, I hope so.