Is this illegal what my school did? Or nah?

im in 10th grade,
in Australia.
for 6 months ive been struggling with math and the school promised me they would change my math class to basic math(foundation), i have been failing every test and i just completely don't understand it, some parts i do but then BAM they add something or i miss a component and i end up completely confused.
the school said if i go to school everyday then they will change it.
its been six months later and the other day they pulled me outta class basically put me in this room and terrorised me, even knowing i have social anxiety and depression i broke down and just couldn't handle there questions.
anyways i asked if they are changing my classes cause its mid term and im failing dreadfully.
they responded with you broke the deal so we aren't changing anything.
first off isn't it illegal to make a deal with a student?, and if a student is literally failing the subject and not doing any work then why aren't they changing the subject making it less stressful on me.
i told them my side of why i come late, which is all truth.
-i have anxiety disorder and i feel sick, my mum has been sick (she has phenomena:/ ), and we live really far so it's hard because i have to catch 3 buses to school and the buses come late all the time.
- and even if my mum could drive us we have virtually no money for petrol because we are about to loose our house because we live in a big house our mortgage is really big.
Added (1). they said oh i don't know what to say about that.

and i said so can you kindly change my classes so it will take the stress off of me?
and they said no because we made a deal.

i asked my mum and she said there was no deal.
after all the stress i ended up catching the wrong bus home
Added (2). And now im still shaken up and having anxiety attack.
i can't even think staight.
argh

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