Well after waiting on the phone for over 30 minutes I finally got thru to a call centre rep based somewhere in Wales, UK.

The guy was very apologetic about what had happened and admitted to me that as yet they hadn't been informed as to how to handle the change and were just as much in the dark as I was.

He did say that because we had through flights, he thought we might be handled different to those who were simply travelling between Hong Kong & Sydney.

Personally, the worse case scenario for me would be that VS would put me on another carrier for the flights between Sydney & Hong Kong and travel in economy class. If they put me onto a CX flight, providing I can do daylight flights, I could see myself coping with that assuming I kept the upper class bookings for the longer sector flights between London & Hong Kong.

Anyway, I'll camp on the phone tomorrow and see if VS have worked things out.