I am not sure I fully understand the timeline, or flights. What is important is not the ticketing rules, FF status etc but DOT guidelines.

In accordance with US Department of Transportation rules, customers who purchase a ticket in the United States for travel on Qantas may cancel their reservations and have their ticket refunded without charge within 24 hours of ticketing when the ticket is purchased one week or more prior to scheduled departure of the first flight in the itinerary.

https://help.qantas.com/support/s/ar...flight-booking

Key questions are did you book through the US or AU website or agents? And departure date appears to be 21 days so outside the 7 day limit. And was this for a flight originating in the US to AU or AU domestic. The QF wording seems quite vague. In any case I would push back, and do a CC charge back as QFs wording is quite clear but may not be correct - not your problem.

I have have never had an issue QF and DOT refunds, but in each case it was obvious it was a ticket for pax inside the US.

(With hindsight I would probably advise, esp. with QF against cancelling due to a CC preference...)

KF