FJH
Just as a thought if you are sure you've sent in all the right docs and they have recieved them have you though about the small claims court. If the RAF are holding your money you can go to court to claim up to £5000. The threat of taking them to court worked for me. Gave OC Accts (I think) 14 days to pay or I would take him to court at the RAF Rep.
Hope you get your mony soon.