There is no reason the committee cannot engage a broker direct to place your building insurance. And you should, as a matter of urgency, because if there’s eg an injury or large claim every owner is jointly and severally liable.
Just make sure you engage a specialist strata insurance broker like BAC Insurance Brokers or Strata Fair (flat fee service).
Then, if the errors were made by your strata manager and they are not responding to committee contact, leaving all owners seriously exposed, make a complaint to NSW Fair Trading – https://www.fairtrading.nsw.gov.au/help-centre/online-tools/make-a-complaint.
Cheers Karen