I didn't have your issue, but I had another issue with AT&T. This is a sort of long story, but here goes....
Basically, I waited on line Friday from about 7:00 AM to about 2:30 PM at my local Apple store. I finally get inside, pick out my Black 16GB 3G iPhone, AppleCare, and a anti-glare film set. The Apple sales person starts my transaction with the handheld they use, enters my information, and he gets an "unsupported account number" error. He tries again thinking it was a glitch, and gets the same error. He calls AT&T and they say that my account is fine. He puts me on the phone with them and they ask if I had a corporate account. I reply no, but I used to get a corporate discount and had it removed the week before as instructed in order to purchase the iPhone. The AT&T rep on the phone tells me that they are having an "issue with personal accounts that received corp discounts" and that I had to go into a corp AT&T store to have my account fixed. At this point I was quite unhappy, but drove to my nearest corp store anyway figuring I had time to resolve the issue. They were out of iPhones, but I spent over an hour there making sure my account was squared away. Even got a rep to put a note on my account to this.
Back to my local Apple store I went. I called ahead, spoke to someone on the floor and explained my story. They allowed me to cut the line that was still there, and attempt buy an iPhone. I went back in, started the transaction, and the same error comes back. We call the AT&T line and they basically say I have to buy the iPhone in a corp store that there is nothing they can do even though I am clearly eligible (the AT&T rep even said there should be nothing wrong with my account). So after waiting in line all day, going back-and-forth between Apple and AT&T and no iPhone on Friday.
This morning I woke up early again, went back to the corp AT&T store, and was able to purchase my new 3G iPhone this morning. Luckily, they had gotten a restock shipment and they were able to process the order. Needless to say, my Friday was a complete loss. The only saving grace was the courteous Apple employees that went out of their way to help me yesterday, even though I couldn't buy an iPhone. The Apple employees seemed to know more about the process then any of their AT&T counterparts. Like I said though, this story ended happily (like yours) as I was able to buy one this morning.