My understanding is that Section 46 of the Act does allow an Owners Corporation to authorise a payment to a committee member in recognition of the services they have performed during the preceding year.
However from your post it sounds like a committee member/s are contractors providing services to the building. I think as kaindub mentioned that you should raise this at the AGM and agree with the OC on: 1. a contractor selection criteria and bidding process that is transparent and competitive; and 2) contractor documentation requirements.
If discussing at the AGM is not an option perhaps you should be considering mediation, via NSW Fair Trading to resolve the disputes: https://www.fairtrading.nsw.gov.au/housing-and-property/strata-and-community-living/resolving-disputes-and-mediation