Sorry to have left you folks[1] hanging like that - there was an ending to this, or sort of an ending.
I did get a "final" bill, which was an exercise in obfuscation, and verified that they really cannot control their billing at all. I mean to scan and post it, because describing it just won't do, and it's unlikely anyone would believe it anyway. Really, it's that lame. :)
Since the amount they claimed I owed was under $20, I paid it to make them go away. This seems to have worked, because I've heard nary a peep since then, and if they were still including my account in their system, I'd have received another bill by now.
Oh, yeah, and my email account is still on.
Will add the scanned bill in a couple of weeks, when things settle back down again - I'm off to a conference and then, of course, there's Halloween.
[1] I'm making an assumption here - that all the hits I'm getting are from folks actually reading this tedious thing.