It has been established in law that the Owners Corporation has full responsibility for maintaining and repairing common property, regardless of whatever claims they may have against anyone else.
I can only recommend that you speak to a specialist strata lawyer about what claims you can make but it would think loss of rent because of the leaks, repairs needed to your property and a demand that they get this properly fixed NOW would be on the agenda (plus any legal costs that accrue).
They will advise you on the best course of action but I would also say, if possible, do anything you can to avoid taking this to the CTTT which is a lottery and which can't award costs.
Don't forget, it's none of your concern who should have done what and when – the OC has to maintain and repair common property and face the consequences if it doesn't. However, they should be having a hard look at their building manager if this is the level of service they are getting.
JimmyT