Hello ArkG,
Welcome to Microsoft Community.
It appears that you have consulted the information in the support link below and tried to unlock your Surface Duo:
Unlock an AT&T locked Surface Duo - Microsoft Support ****
Normally, AT&T will send the order processing information via email, but if you don't receive any unlock code, please wait a while to see, because you may not be able to do anything without one.
If you notice that you are consistently unable to obtain an unlock code, then you may want to call AT&A and contact AT&A's support team, here are the appropriate phone numbers:
800-331-0500
If AT&T is unable to assist, I recommend that you contact Surface Duo's technical support directly and ask if they can help you more with this issue:
Get service - Microsoft Support****
I wish you all the best.
Best Regards,
Mitchell | Microsoft Community Support Specialist