An update: NBN co did indeed come out - earlier than planned - on the Labor Day bludge day, 3 days after I lodged the ticket on the prior Friday evening.
They were here for around 10 min max - simply replaced the connection device and ran the tests.
And suddenly Telstra upgraded the plan for us for the same monthly price to 100Mb/s...and we get that nearly 24/7

Just ran an Ookla test in the middle of the afternoon and it spat out 92.24 Mb/s down, 18.77 up. Definitely fast enough for this chicken (our prior pegged at 54 down was fast enough - it rarely dropped below that seeing we were throttled from a 100 cable line)