My teacher is trying to drop me from a subject and IDK what 2 do, any advice?

I take additional maths, in my school you need a 7 to take maths A-level, I want to take maths A-level. Two times in a row I got a 6 in my maths exam, although last time I got a 'passing' grade in my Add maths exam. This time I didn't as I was very stressed and preoccupied with other things, on top of this I had a my maths paper 1 resist (I missed the OG date) on the same day (the paper which always gives me trouble). As mentioned before, I got a 6 again but this time I done very bad on my Add maths exam. My teacher said that because I did bad on my exam and didn't get a 7 that I can no longer continue with Add maths. I know that I I had more time to revise (the exam was right after the other mocks, where as before it was a week or 2 after) even just a couple days, I would have performed better. I asked if I could do another paper 1 because I had been revising since I got my grade back and had made a drastic improvement. An he said he was unsure. I also emailed him asking if I could sit another Add maths paper next week he has not replied. I Don't know what to do, Any advice?