In NSW I have complained to Fair Trading about a badly performing strata manager by pointing out he failed to comply with what is required of the realtor’s licence holder eg being honest. The complaint was pursuant to the Property & Stock Agents Act. My complaint was upheld and soon afterwards he quit as strata manager.
Call your equivalent of NSW Fair Trading and ask what legislation governs the CONDUCT of strata managers.
Tell them you wish to file a complaint.
Once you are made aware of the relevant legislation, have a look at the Table of Contents of the Act or Regulation for terms like “conduct” or “behaviour” etc.
Best of luck!