I had hoped someone else would have jumped in on this, but here goes. I think you are fighting the wrong battles with the wrong people.
Firstly, this doesn’t sound like an insurance issue to me. It’s a failure of common property which is usually not covered by insurance.
So you have two parallel routes you might take.
You could seek orders at NCAT for your owners corporation to fix the problem – forget all the personal stuff. They have a responsibility under the law that’s as clear as day. You will have to go to mediation first and if they then say they’ll do it, don’t leave without a written undertaking to get it done in a certain time frame.
Then you could take a civil case against the OC for the loss of rent.
But before you do any of that you really should consider consulting an experienced strata lawyer.