QF bad to good

So, I was booked on QF774 but arrived at ADL six hours early. I asked at the sales desk about switching to an earlier flight, they did the research and found that they'd have to charge the difference between my fare and the actual one as mine is a combined flight back to YUL. They put me on the phone with the international sales agent where I had to wait for thirteen minutes before someone answered and he gave me the same spiel, though he said I could ask at the service desk, explain that it is an internationally booked AC flight but could they put me on standby for an earlier one.

So, with that, I checked in my QF774 flight, passed through security, found a QF service desk, asked exactly as instructed by the sales agent, and lo and behold I am now on QF756. Yay! I'll arrive in Sydney four hours earlier and may actually have some daylight to go visit a little bit.

So the QF bad was the sales agent saying it wasn't really possible unless I paid a large amount.
The QF good was the service desk accommodating me.