Am i going to fail and stay down?

i got a D in english all because of a stupid twilight film techniques essay. apparently i wrote the essay properly but didn't talk about the film techniques. my teacher says all my other has been very well done, and i still got a fricking D!!!! WHAT A LOAD OF BULLS.H.I.T. alright so i live in Aussie WA and do we have this thing where if you get a D you fail and don't go up a grade. or is that just a whole mob of babbled bullshit