Never Use Orbitz From Australia
UNKNOWN -- NEVER, NEVER, NEVER use Orbitz from Australia. You will lose all your money if you try to make any changes. You have to call an international number (not toll free) which take my word for it, will never answer (or more accurately the International reservations section will never answer) - I wasted over 30 minutes in the course of 3 calls this way. I had to give up and kiss my flights payments goodbye.
There are far better online booking services you can use, but keep away from Orbitz.