The offender claims that they had verbal permission from the previous strata manager
As legendary Hollywood producer Sam Goldwyn famously said, a verbal contract isn’t worth the paper it’s written on. Ask the committee to politely invite the offending owner to submit an application for approval, including the necessary by-laws, or remove the air con, or have it removed by a contractor at their expense. If the refuse then consider taking action at Fair Trading and NCAT under section 232(2) of the act for failure to fulfil a statutory duty.