I do not want to change flights, I accept I should have to pay if I need to change flights. I want to stay on same flight but change class and give them more money on the same flight.
Even NZ (who getting pretty tight on things) will let you change from economy to business without charging the contact service fee.
Not an economist but very basic thinking to me is that if someone wants to give me more money, then silly to discourage that by telling them they have to pay for the privilege - accept better seats etc but really, turn down money unless we pay extra!
Probably my thinking is the reason I generally only book business and as this was to be first time on QF wanted to let boss see economy, but then have surprise upgrade bought which boss couldn't see.
Never mind, my mistake and I know for next time who and how to book.