The by-law isn’t “null and void” but it may have been breached. Did it say that the commencement or resumption of work was contingent on council approvals? Or just that approval of the work was dependent on council DAs? If the latter, the rogue renovator could argue that all he or she was seeking was approval after the work had been done.
Any work that involves the reconfiguration of the rooms in an apartment requires council approval. My next call would be to the council’s planning department asking them to investigate. They can issue a ‘stop work’ notice if need be.
Failing that, you could apply directly to NCAT (no need to go to Fair Trading on this) for an interim order that all work cease until appropriate approvals have been granted. Go to this page to find the links to the necessary forms. You apply for an interim order under Section 231 of the Act.
If the rogue developer is smart, they will get the builder to say this is a complying development – which means no council involvement. Don’t fall for it and if they try it on, tell the builder you will report them (not the owner) to Fair Trading for fraudulent behaviour.