There is no way you should be paying a special levy to make up for those who won’t pay. Instead you should be looking fro a strata debt collection service who will get all the money for you at NO COST to the owners corp. Google ‘strata debt collection’ to get a list of companies.
If you need to raise the money to cover for a shortfall, contact Lannocks, who are sponsors of this site, to organise bridging finance.
And if your new Strata Manager can’t sort all this out for you, they’re not much use. It is illegal for the old SM to hang on to your documents and finances. If your SM won’t do it, call Fair Trading (13 32 20) and get them on the case.