Just my five cents worth, as they don't make two cent pieces anymore...
Have you considered going to a Local Court and sitting down with a Chamber Magistrate? A Chamber Magistrate doesn't sit on the bench in judgement, and to the best of my knowledge, there's only a nominal fee charged. They won't be able to solve your issue - they don't act as solicitors - but they will be able to guide you with the best approach to take.You generally need to make an appointment in advance.
Another option is to consider contacting the NSW Civil and Administrative Tribunal
https://www.ncat.nsw.gov.au/ From what you've outlined, the matter may be able to be heard there. I believe doing that may be limited by the value of whatever transaction has taken place, so do your research first.
I'm certainly no solicitor, but these are just thoughts / alternatives to consider.