just involve your parents our threaten legal action and you should be right. if you meet the attendance requirements and work requirements it'll be hard for them to not let you take the next sac and hence fail you, because behaviour is much more of a subjective thing, opinion based. did you get warning or anything?
theres little chance it'll stand, they wont do it if you bring in parents etc. i know someone that was going to have this happen due to attendance even though they'd just been sick, and i was threatened it except this yr in yr 12 gar for not completing work requirements (ie any homework) ha but they didnt go through with it. most dont. just get your parents to be really pissed off haha