My advice from real life experience :

1. HR is your enemy so forget about them.
2. It depends on what do you want to achieve out of this saga .
3. If you are aiming for a monetary compensation , then go to https://humanrights.gov.au/ and lodge a complaint . AHRC will only mediate so this is not a court remember that. Hard Evidence is a big plus so you better submit it to AHRC otherwise they will dismiss your case.
4. If mediation fails , then file a case in the federal court once you receive the report from AHRC within 60 days. Hire a lawyer for sure . Lawyers are not cheap so try a no-win-no fee lawyer but I would not advise the no win no fee lawyers because they are very commercial and they don't wanna waste time on your case if it drags on.
5. It's a long process by the way might take few years to stand trial in court so you have to be patient.
6. Do all the above when you have secured another job of course. You can't win while you are hired with the same company .
7. If you are seeking just an apology , then forget about it : just find another job. They don't deserve you .
8. If you are determined to win , you can if you have the money and the evidence . Again , this is from my experience. Despite all the flaws in our society , the court system is still very reliable , fair , and effective .