AirBnB is a Ripoff

The property I chose in Sydney was advertised on AirBnB in Australian dollars. AirBnB charged me the correct amount, but in US dollars. This equates to about 830 Australian dollars more. I spoke to my host-she gets quite correctly paid in Australian dollars. I have so far spoken to two AirBnB customer service agents to rectify the problem. Both of them could or would not understand the basics of foreign exchange and think that I am complaining over the price of the property!