Any management rights agreement is a contract, and like any contract it is binding on both parties to it.
The only way to vary a management rights agreement is usually:-
1. by agreement between the parties via some form of commercial negotiation, where neither party is forced to agree to anything unless they want to; or
2. through a lawful mechanism under the agreement itself (like a market review of caretaking remuneration), which might set out how a disagreement is dealt with via through the decision of a third party.
Under the BCCM Act there is also a third way - a statutory review. A statutory review can be triggered by either the body corporate or the caretaker in a set of very specific circumstances.