Thanks Michael I appreciate this

Countries sometimes prosecute citizens for crimes committed abroad -- for example, in the case of sex tourism. So since the owner is Australian, it could be worthwhile to research the relevant Australian wage theft / forced labor laws. Then depending on what you find, you may be able to credibly tell him that if he continues to withhold your salary, you will file a criminal complaint against him for violation of [such-and-such law].

You might also contact an Australian attorney about suing the owner in civil court there, as I would bet he has assets in country. Of course you will need to weigh the time and cost involved against what you stand to recover, and those factors will vary depending on whether an attorney will work on a contingency basis, whether punitive damages are possible in excess of the base amount of wages at issue, complications relating to jurisdiction, etc. But at a minimum, a letter of demand from an Australian law firm (or even just telling the owner you have contacted legal counsel there) could be enough to persuade him to see reason.

IANAL and the other standard disclaimers.