The appropriate response would be “Please don’t quote non-existent laws at me” followed by “if you don’t want to represent people, why did you join a committee?” And that would be followed by “oh, I get it, to serve your own interests!”
“Invasion of privacy” is a made-up law but the critical thing here is a committee member refusing to engage with owners to discuss issues relevant to the strata scheme.
The long game on this is to start a website or newsletter alerting other owners to the problem so that these people get voted off at the next AGM (if enough of them agree with you).
The short game is to put motions on to the agenda for your next EC meeting and then turn up and ask to speak. If they don’t allow you to, ask for that to be minuted.
Other options include
Applying to NCAT for an interim order preventing them from spending the money.
Filling in a form requesting mediation at Fair Trading.
Applying to NCAT for orders under section 232.
You have options but a first step should be a letter to the secretary asking them how owners are expected to communiate with the committee and how the committee should be expected to respond. Just that. No “he said, she said”. A simple question requiring a straight answer.