It depends on the nuances of the specific contract. A merchant as big as Qantas would have bespoke contracts with several acquirers most likely. In many cases, the interchange fees paid to the scheme are refundable, but not the assessment/network fees and whatever markup the acquirer/processor charges. In addition, the refund transaction, which is processed separately, will have its own network fees and acquirer charges. It's probably simpler for Qantas to simply not refund the fee, and even though they may collect a refund of the interchange fee portion, they are using this to fund the extra processing costs of the refund. As best I can tell, the ACCC's guidance on payment surcharges doesn't specifically cover what happens in refunds, so that's no help if this is valid or not.
