I booked a Business flex fare. I later found the same flight cheaper at Amex and was able to use an Amex travel cashback offer, so I cancelled the original.

Qantas refunded minus a 300 NZD cancellation fee and now claim that the fare was a Business Saver.

I have screenshots I took while booking that show it was Business Flex and the fare conditions state fully refundable if cancelled before departure.

Qantas just say nope, it was a Business Saver fare.

The only documentation I have is the Qantas e-ticket which has the travel class but doesn't state a fare code or type.

Banging my head against a brick wall telling them it was a flex fare and they seem uninterested in treating my screenshots as proof.

The booking I made at Amex saved me what I'm currently losing on this cancellation charge, so it's not the end of the world, but it's the principle. I was shown fare conditions while booking that said fully refundable, and I'd really quite like to have my 300 NZD back.

What can I do next?