I helped a friend on a captivate once with the same issue. She had a friend that changed it while they were drunk, and then forgot the code to tell her in the morning. Anyways, I put the phone in download mode and odin´ed her captivate back to stock, worked like a charm, no more code. It may suck having to set up your phone again if you didn't have a backup, but it should get your phone unlocked without having to call up ATT.
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