The Act sets a limit of two months for the OC to respond to requests for action – and that includes saying no or saying nothing.
The Act simply says that the OC must maintain and repair common property and various legal rulings have established that this can’t be delayed by secondary issues such as having to wait for the outcome of a related court case (like suing the developer over defects).
The OC needs to establish a reasonable and realistic program for doing the work and finding the money to pay for it. Otherwise you can seek orders at NCAT compelling them to do so. This should be made clear to them at mediation which is an important step towards doing that.