Am with you on this one 77W! I too keep getting "fdp cc" (what the bloody hell does that mean?!!) as a reason for rejection on the swap shop. I have also sent an email to the swap team and have received the same computer generated reply that you have got. It is really frustrating! I have received loads of swaps for a flight that I don't want to do but I cannot do anything about it!
Is it for a flight u called sick for in the last 2 months cuz i did for this particular flight! Maybe...just maybe they are blocking it from getting swapped!!!!