Interview was moved to a different district, although I didn't move out of district
Here is my short story. Me and my wife applied in March, 2016. We were scheduled for interview in SF district for August, 4. Few weeks before the interview we submitted address change request and later got our confirmation letters. The new physical address is the same city and the mailing address is the different district. Everything remain same for my wife but something wrong happened to my case. It was cancelled and in few days scheduled again for August 30 but in the _different district_ - the Santa Clara district where my mailing address is in.
I have used this firm for a number of years for H-1B visas. They are extremely professional and organized. And most recently I had an employee require H-1B status quickly due to a student visa heading toward expiration. We did the premium process through this group and the approval came back in much less than the 15 day turnaround time. That in itself should tell you everything you need to know. If you don't hire this group, you are doing yourself a disservice.