I have a locked surface duo.

Hello!
I bought a surface duo with an at&t lock.
I used the at&tunlock service to release it, but it doesn't move on with the warning "technical issue".
I personally asked Microsoft about the issue, and a few days later they said it had been handled and recommended that they try the at&t unlock service again.
However, similarly, only the "technical issue" warning window appears and does not proceed. 
I would like to ask for a way to deliver my device's IMEI and request to unlock it or a personal email address.
Thank you.