So I called Qantas again and after a very long time on the phone and a talk with a supervisor they've landed on the fact that we will be charged A$300 dollars for our bag in line with their excess baggage fees for flights to the US.

Apparently we aren't entitled to a free checked bag as per their normal transpacific flights because they go by AA's original allowance which is 0 for our tickets... But then they also don't charge AA prices for the extra bag which would have been $75 dollars and instead charge theirs.

We aren't allowed to purchase an extra bag in advance at lower fees and it has to be done at the airport where we have to pay their excess baggage fees...

Does this seem correct?!