Good luck arguing, but you are not the first and you will not be the last. However, as other posters have mentioned I doubt if you will have much success.
The official line is that your pension is not reduced if your PVR - you are paid what is due to you. Why the reduction? Well it is because in AFPS75 officers receive a bonus in their pension if they leave the service at the specified options points (16/38, 22/44, age 55) - this is to encourage people to leave at these pints which, for the RAF, greatly eases manpower planning. You decided that you did not wish to leave at one of these points so the MOD decides that you do not qaulify for the bonus.