My teachers won't let me take the higher science paper, I NEED to for A levels

I want to do medicine, if I can't do Chemistry A-level then I can't do medicine.

I've been to every college local to me (in a 1 hour radius) they all said the same thing. No exceptions.

I know it's the teachers decision but is there not another way? Apparently its set in stone and that's the final decision that I'm taking foundation science but it's destroying my dreams. I've tried to get my parents involved but they agree with my teachers, I'm at a loss on what to do. I feel like I've tried everything.

Advice?

EDIT: I only have predicted 5s because its the best I can get in the paper I'm doing. When I was doing higher in year 9 I was getting 9s in biology, 8s in chemistry. It was my physics that dragged me down to foundation. Or I assume so anyway.