I was trying to purchase 2x domestic tickets on AA this evening from LAX - MCO. The US site was pricing cheaper than the AU site and allowed me to select preferred seats (row 17 with the middle seat blocked) and without having previously been aware of this thread, when I tried to purchase with my AU credit card, kept coming back with error. I put the reservation on hold and had to pop out for a while. When I came back I tried one more time paying with my AU credit card, entering Australia as the country and my Australian billing address, except leaving the postcode box blank. It again came up error and at this point I searched AFF and found this thread.
I was deciding whether to call the AU call centre to pay for my US site booking that was on hold or to just book through the australian website, however now I notice that my booking has somehow been ticketed and the final price has gone up $100USD! I'll have to wait until it comes up on my credit card account to know how much they charged me, but has anybody else ever heard of this happening?