You may need to try contacting via SYD or even SIN. I think there should be a coordinator - very slack if they haven't been in touch in 5 years of being PPS.

Yes I have seen very few seats pre-selected on a full flight before. Eg at OLCI only half a dozen seats on 747 already taken and the run of every other business seat, yet business class was totally full.

From the info you've posted I'd be tempted to change routing to go through LHR (308 and 320 look much more likely to clear waitlist than the others).