Sue in small claims court. This exists in Australia:
https://www.fcfcoa.gov.au/gfl/fairwork-small-claims>
The law is what provides justice, the mechanism is the court system. There are many who try to dissuade you from this option because it is effective. Use it.
Write your consumer protection entity. In much of the US that is your state attorney general's office. I believe you can start with the ACCC (Australian Competition and Consumer Commission), here:
https://www.accc.gov.au/consumers/problem-with-a-product-or-...>
Write your government representatives.
- City council members.
- County supervisors / local councils.
- State representatives / MRA.
- Federal representatives / MPs.
Call their office(s).
Write their office(s). Email and postal mail.
Follow up with them. If you don't get a sufficient response, let the office know.
Australian governmental organisation: https://peo.gov.au/understand-our-parliament/how-parliament-...>
Contact NGOs advancing personal digital rights in your country. For Australia this seems to be Digital Rights Watch (https://digitalrightswatch.org.au/>) and EFF Australia (https://efa.org.au/>). These and similar organisations elsewhere should already be very familiar with account-lock-out and similar problems, and can likely direct you as to how to register your claim most effectively.
Tweeting, blogging, and throwing up your hands is what Meta would most like you to do.
Do more and cause them pain.
Organise.