My parents won't let me buy protein shakes?

I am 15 and I started lifting out a year ago. I have a big problem, my parents are not letting me buy protein shakes or creatine? they think its dangerous or something! I really need them because I am not getting any results in my workouts anymore because of my low protein nutrition and shakes will help a lot to add these extra 20g protein left in my body. They think it will stunt my growth, build my muscles in a wrong way and that it will give me kidney problems? I don't really need creatine, and it would be very hard to convince them on that, but protein shakes??? how can I convince them? they are talking crap and I feel really pissed hearing all that ignorant facts they tell me and I cannot say anything because they insist! any way to educate them???