Wrong currency in checkout

Hi there,
I’ve been using your Currency Switcher plugin for some time now and it’s great.

We used to allow people to check out in different currencies but mid-January we stopped that and only allow checkout in USD. The Switcher is active so people can see the prices in their local currency.

In the past week, two orders have gone through in AUD, for the USD amount. This results in a significant loss of money for us.

Can you please help us understand what is going on?

Would love to figure out what’s happening and stop it from happening again. Could it be a cacheing issue? Thanks.