I guess I have to go back to the principles office. (This is what it feels to feel absolutely powerless...cause that really sucks)
Thanks for everyone here
If you have just joined a school, can a school block you from doing a subject? What are the legalities of this? What to do if they are adamant about this? (Maths extension 1?)
P.S The school is a relatively good ranking school and my previous school marks for (Maths) were A's and B's.