Villageidiot,
You have indicated that your SP was registered in about 1964, are the ac units installed in the balcony window structure?? Under the original strata act balcony wall, door and window structures were considered lot property (not common property). But this does not address the matter of compliance with the by-laws, being in particular appearance of a lot.
From past experience at Fair Trading, you will need to mediate and then seek an order, but they are likely to issue an order, but this could involve the OC being made to pay for the work to correct the situation, as they had not acted sooner.