You should ask for written documents - your employer is legally required to give you two things in writing: 

• A certificate from an independent doctor stating you pose a significant risk at work or are unfit for the job; and
• A statement explaining why they cannot make reasonable accommodation for you. If they cannot provide both, the law presumes you are fit for the job.

File a complaint with the Complaints Officer at your workplace.

If unsatisfied, approach the Ombudsman in your state.

You can also go to a civil court directly for any violation of the Act, or in appeal if you are dissatisfied with the decision of the Complaints Officer or the Ombudsman.