Originally Posted by
bocastephen
No, changing a flight, routing or date would trigger the change fee and fare difference - the buyup is only for moving from coach to first on the exact flights you're currently booked on.
There is a cumbersome workaround.
Buy up to a changeable far without penalty.
Finish the call.
Go online and change to the flights you want.
You will get a voucher (not cash back) for the difference in fare.
This is really only good if you are planning to use that difference (which could be hundreds/ thousands of $.