Gsce subject changes

Hey there, I picked design technokogy for my gsce,to be honest I kind felt peer pressured to pick it. I convinced my self I would enjoy the subject even tho I never took the subject seriously in yr9. We are 3 weeks into the subject and I want to change to phycology. Design technology is judt not for me and to be honest the machines freak me out. I want my parents to call the school to let me change as they don't allow students ro change subjects. But I don't know what to say and I don't know if I should wait for the term to end or call on Friday. Someone please help me out