My teacher was a bitch and hated me and gave me an extremly biased mark for my assessment (15/20 whilst my assessment was a lot better than the person who got 18/20). She no longer teaches at the school (she knew she was leaving before she marked the assessments) and marked me far below what I believe I should have got.
No offense, you're hardly an unbiased source. What godly intuition told you that your 15/20 was better than someone else's 18/20? LOL, 'marked me far below what I believe I should have got' - I don't think there's too many students that have done (relatively) 'badly' that would be like 'yeah, shit I did do badly'. A lot of students will find other things to blame, like 'the teacher who has always hated you'. So yeah, no offense, I think it may be you trying to find a way to pass off blame to someone else for perhaps a little blip on your part.
How did the teacher know it was your paper anyway? Don't Year 12 assessments require student numbers, so the teacher doesn't know the student?
Is it possible to request an assessment to be re-marked? If not, do assessments and such significantly effect your final ATAR mark?
The policy varies from school to school. At my school, they would only mark English if you formally appealed, but if your appeal was rejected, you lost a mark. If you were successful, you got your new mark. This way they only ever got like two appeals the entire year.
If not, one assessment in school, particularly in early days will not significantly affect your ATAR at all. I guarantee it. Good luck.