YOu need to look at the strata management contract
It will say what is included in the fixed fee, and what is schedule B fees
But just because it is included in the fixed fee does not automatically make it a schedule B fee. Remember this is a contract signed by both parties ad is the entire agreement. If a party left something out, then the only way to have it included is to amend the contract with the AGREEMENT of both parties.
The strata manager (or the OC) cannot just at a whim move the goal posts.