We all love to hate AT&T. But I did have a good experience with AT&T. I have been a customer since 20 years or more. I get a new iPhone each year. So my old iPhones are immediately available to unlock when I buy new ones. I did not do so this year. One of the iPhone 5 broke and we use Apple Care to upgrade it - thus changing the IME number. AT&T refused to unlock my phone because it was not the same as the one I had bought originally. I posted and got help from these forums. It took about 6 weeks but my phone was unlocked today.
Thank you very much for these discussion forums. Perhaps the whole process can be made more efficient by incorporating Apple Care repairs by better communication between Apple and AT&T but at the end of the day my job got done - and the main reason it got done is because of the customer care people (Dmitry especially) on this forum. BTW the phone support was absolutely not helpful.