Just some general points from my perspective as a teacher. I don't teach English but I've found a few of your points interesting that i'd like to comment on:
she delibretly gives students bad marks at the start of the year, and slowly increases them so she can make it look like shes a great teacher and that we made progress because of her.
If you
genuinely believe this is the case and not basing this completely off rumour, then speak to the Head of English. This is unacceptable and
needs to be addressed ASAP.
I got 70s, for both my essay and creative piece for To Kill a Mockingbird over semseter one, and when I complained to her she kept telling me my writing was average.
1) 70s is still a fairly decent mark.
2) Get your essay cross marked by another teacher at the school who teaches English to confirm. You don't need feedback from the other teacher to get feedback from somebody else. I assume it was typed? We all live in denial at some point in our schooling, that we're much better than we'd like to admit
It may be the case that 70s is actually where you were at, at that specific point in time.
I do understand your frustration though, not having feedback to identify why you received a mark in the 70s as opposed to an 80s or 90s mark is completely fair.
I even stopped reading for leisure which I used to do regullarly.
Sorry, but that's an absolute load of rubbish. If you wanted to read for leisure, you would. Don't blame the teacher for this.
She also didn't write me any feedback she just gave me the score.
Head of English or coordinator. Definitely. You are entitled to some feedback for improvement, and any good school would enforce a policy that makes sure this happens.
because I knew it was corrupt
Well, no, you don't really know that it is. The idea of a year of schooling is to see one year's worth of growth (well that's the mantra, anyway). It could genuinely be case that you are in fact growing and learning, and as a result, achieving these high scores.
tl;dr - if you genuinely believe something is going on, let somebody know about it because it's unacceptable and should be dealt with, regardless of what year level its at. I'm sorry you had to deal with this because majority of teachers are extremely ethical and will spend hours and days providing students with personalised/individualised feedback for improvement.