Just over 90 minutes later, I received an e-mail back from telesales, explaining that if this is done through the London office, then a service fee will be payable.

However, as London had not yet processed the changes, telesales offered to take over the booking and make the change with only the AUD 38.50 change fee (now including GST, of course) + fare difference. I said yes please, and a 45 minutes later had another e-mail back saying that they were doing exactly that.

The ticket has not yet been reissued, as far as I can tell, but it seems that all is well, I have saved the GBP 25/AUD 60 service fee, and learned a lesson about how to do it in the future.

And QF has impressed, and earned more than GBP 25's worth of goodwill.

Funnily enough, I can currently see the booking in ba.com (it has my BAEC number in for the 12K oneworld bonus) and checkmytrip.com but not on the QF website.