This is both not uncommon and often difficult to deal with. I'm not familiar with the NSW rules specifically, but in general terms general members are entitled to review the records of the organisation. Committee minutes may be restricted - but as a committee member they should be accessible. Financial reporting requirements are a 'big ticket' item as this is required for compliance with the legislation.
The thing is, in practice, I've found that the methods to enforce these rules is often rather lacking. Regulators often aren't keen to get involved unless the committee as a whole are behind the push. Courts have determined that there has been a breach of the requirements but refused to remedy (admittedly, in other states - so your situation may be different) - To explain: there have been cases where members have been kicked out, the Court has agreed this was improperly done, and has declined to order they be reinstated due to reasons such as disruption for the rest of the membership.
In practical terms, here is my suggestion for the best thing you can do: Motivate the voter base (i.e. the members) to get the bad apples out, replace them with a new, clean committee, and then go through the records to see if there's anything that requires action. To do that, you'll most likely be identified as a trouble maker. Those attacks will increase. They'll likely try to get you discredited, kicked out, and possible worse. It won't be a pleasant exercise. The more ingrained and extensive the 'corruption', the harder it will be.
