If you want the option of transferring your money back overseas, you need to show a international tranfer of your original funds. At least that's how I understand it.
Worked for me. Had a Quantas ticket booked with Bravofly, they wanted £3050 to change date. I contacted Quantas in Auckland and they change date for 135 NZ dollars. I informed them of the crazy price and that was the reason I was there.