Are you sure that you are allocated an AFCO based on your postcode? Never heard of that myself. I'd say just get yourself along to the AFCO that deals with you in the more constructive manner and crack on from there. Surely having to start the process again is a small price to pay for a more positive, constructive approach?
Everyone I know that has applied has gone to an AFCO and arranged to do the subsequent interviews at the same AFCO, none have mentioned being allocated to other AFCOs for interviews etc.
Go ask on
http://www.thestudentroom.co.uk/ Armed Forces forum, where most of the participants have recently or are currently dealing with AFCOs and the selection process