I am a current PhD student but recieved bad news about my Masters. My thesis was, in my opinion much better than the grade accorded to it and I was very suprised to recieve such a low score which does not mirror my other results at all - what should I do, should I just leave my Masters as it is and accept it or should I contend my thesis result? I have passed but just a few points short of merit, if my thesis had a few more points I would get a merit.
Any opinion?

I think I'd suggest doing two things:
1) make an appointment to see your MA thesis supervisor to get more detailled feedback
2) check the university's rules to see under what grounds you can actually appeal - often you can't just because you think you ought to have got a better mark.