Brake Promblems with my Scooter Peugeot speedfighter 2?

I have a question myself, i was riding my scooter speddfighter 2 quite fast and all of a sudden i felt the bike like it was losing power, like some one had put the brakes on , i was going downhill , then the bike suddenly went faster and i tried to slow it down but my rear Brakes had gone. the brakes must have gone cause they jammed and over heated. this has happened to me a few times, you will be just driving and the rear brakes Jam and the bike has only 6000 km on it .has anyone had this problem???? if so please email me on clubwavewatersports@yahoo.co.uk
if maybe you have an answer
Thank you