Changing O class CX booking made through QF

[Isochronous]

Have a CX HKG-PEK leg booked and it might be preferable for me to leave HKG a day earlier. This is an O class booking so was curious as to whether:

1. Should I ring CX direct to change or go through QF - in terms of minimising fees?
2. I logged on to QF and can find Classic Awards available in Economy for the flight I want to change to - does that make it more likely I won't have to pay (or at worst a minimal) fare difference?

 

[fbrimfield]

If it was booked through QF then Cathay have very little to do with it, and they can't change anything, it has to be done all through QF.

Whilst the PNR is valid in Cathay's systems, the E-Ticket number is a QF number, not a CX number. In order for them to be able to control the booking, they'd need the PNR and the E-Ticket number (which was created by their systems).