There is another avenue you might like to pursue. As the manager is clearly acting on behalf of the Owners Corp (NB, not the committee) they have to respond to complaints.
So what you need to to is send them a formal complaint about all the things you want done. Whether they respond or not, you are then able to follow the complaint to Consumer Affairs for mediation and then to The Victorian Civil and Administration Tribunal (VCAT) for a resolution.
You’ll find out more about that – with the required forms – HERE.