Only fix i think could think of is VPNing it back to Australia? Not sure if this will fix given the fact as you're already in Australia.
Also as Garutias said, I've seen this happen a lot. Mainly some Philippine people get their flag switched to USA, Or Some USA people from California get their flag switched to Canada if they live on the coast. And like you some Australians get their flag switched to America ( I've also seen to Japan as well). This is not entirely something easy to fix at all. But should be given a lot of attention to fixing the tweaks as there is a lot of people who have a strong sense of nationalism.