What do I do?

I've received my GCSE results this week and they were disappointing. I failed 3 subjects completely with E grades and got 6 C's and a B in the passes. This includes passes in English Language (higher level)and Maths (higher level). I did a lot of revision, lots of practice papers and then performed below my predictions. I'm not an A * student but I was predicted an A, Bs and C's. I always get on with my work but do find exams difficult. My school believe I'm still capable of doing 3 A levels and will support me closely with my learning to see where I must be going wrong.
In addition my parents are insisting that I change schools and start 'fresh' as they believe the school should have identified I needed more support. I've been looking at new schools but they require a B grade in the A level subjects I want to study. My confidence has taken a real battering. I'm not a difficult student: I get on with my work as I know it has to be done and I've got good friends who are well behaved too.