There are two questions here
1) All you need to do is ask the SC is fix the problem. They are obliged to maintain and repair common property. If they don’t do anything, as it seems, you can go to NCAT and get an order for them to fix it.
2) the process. I’m not familiar with the remediation process, but what you describe is my understanding of the process. It’s up to the SC to follow the required steps not you.
Personally, I’d go the NCAT route. The reason is that the orders can specify a date by which this needs to be done. It’s an enforceable order. If you negotiate with the SC they can drag this on for a long time citing various real or imagined delays.