A couple of updates - after phoning up to ask why I couldn't Manage my booking for my LHR trip, the lady on the phone couldn't answer, but her looking at the booking seems to have done something to allow me to view it. However, now that I can actually view the flight details I discovered that SQ have changed the return journey. It was supposed to be LHR-SIN-BNE-CBR, which they changed to LHR-SIN-BNE-MEL. (The CBR flight was cancelled by Virgin, presumably as part of their Bain-inspired "efficiency" savings.)

Absolutely shocking behaviour (and probably why I couldn't previously view the booking). What were they thinking to put me in a different final destination? And I never received any email notification of the change.

Also not impressed with Virgin, whose only other options are a flight that seems to be earlier than the minimum connection time at BNE, or a flight seven hours later. I asked about an alternate routing, e.g. via SYD or MEL, but the guy on the phone claimed there were no available seats on any other route. I am sceptical, but maybe because this is a Business Saver he was only searching for routes in the same fare bucket.