Side note, this seems like a really interesting itinerary, do you mind sharing (in overview)?
Well, as you ask, here goes...
UA booking, 80,000 miles + approx AUD 300, in business class:
CBR-MEL (VA), MEL-DPS (VA), DPS-SIN (SQ), SIN-HKT (SQ).
LCA-VIE (OS), VIE-ZAG (OU), ZAG-SPU (OU), SPU-LGW (OU) - free "excursionist perk".
HKT-SIN (SQ), SIN-DPS (SQ), DPS-OOL (VA), OOL-CBR (VA).
QF Booking, 150,000 points + THB 16,555, in business class:
BKK-AMM-LCA (RJ), LCA-AMM-BKK (RJ).
BA booking, 9750 avios + GBP 70.50, in business class (Club Europe):
LHR-LCA (BA).
The Qantas booking has now ticketed after I spoke to 4 different agents, 2 in Cape Town and 2 in the Philippines. The South African ones were hopeless, but the ones in the Philippines got the job done. Just to make it a bit more complex, a few hours after it ticketed there was a schedule change, turning my 6-hour layover in Amman to 12 hours. I've accepted the change online and now have a second ticket. I don't suppose it will be the last. What else could possibly go wrong?
Not too bad for a leisurely business class return trip CBR-LON-CBR, with a couple of stopovers in Cyprus and a short one in Croatia (my choice).
As an aside, I noticed on the BA website (I'm BA Gold) that there was plenty of availability from BKK to LCA on Qatar Airways at a better points price than RJ, none of which was showing on the QF website. So I was stuck with RJ if I wanted to use my Qantas points.