As an alternative to a compulsory manager, find an agent YOU are happy with, get 25 % of other owners to back you up; ask the secretary to call a general meeting with the agenda item to appoint YOUR strata manager.
This sort of forces the OC into appointing a strata manager unless they want to be self managed.
The question is why did the OC find this out at such a late stage. The SSMA says the manager must give the OC three months notice prior to the expiry of the contract.
Or was the committee informed and did nothing?