newlsie, the NCAT cannot ‘force’ the OC to carry out the work, technically no one can, however they can appoint a compulsory strata manager with full powers of the OC in the case of a dysfunctional strata scheme. One example of a dysfunctional scheme is one where Tribunal orders are not complied with. The compulsory managers role would be to ensure that orders made by the NCAT are complied with.
As Lady Penelope mentioned, you could try applying for a renewal of proceedings requesting that the NCAT attached a deadline for the work to be completed, assuming one hasn’t already been set by the Tribunal in the order already made.
Another option is applying for penalty order for non-compliance of an order. That may wake your OC up into doing something about this order.