Have a look at this advice on the Consumer Advice Victoria webpage. Contact them and tell them you have done all you can to resolve the situation. At the same time, contact your former strata managers and tell them that’s what you’re doing. And ask your new strata managers if they can make a call on your behalf, just as a favour (they have no responsibilities in this but a bit of inter-profession nudging can’t do any harm).
Come back to us if there is no response