Pay? For the best flying training in the world? Don't you do it 'cos you just don't want to do anything else?
Quite fair to give the OTC a bit of pocket money for digging their own bivvy holes. Don't you think?
I was a UAS student in the....well, a long time ago now. We, the humble RAFVR chaps, got a bit of subsistence and our home-to duty travel, which subbed the odd pint, but not much more. Of course, the University Cadets (APOs) got a special rate of pay which was a bit more generous, I recall, than those of us existing on the standard 'grant' from local authority (made up by your parents if you were lucky.)
Grit your teeth, don't whinge, enjoy the flying and use it as a springboard into military or civil professional flying. You may get less than your OTC colleagues now, but you have the potential to reap more than just good money in the future, but the chance of doing a job you may really enjoy.