I was using JQ7/8 as an eg for the website...
No idea what he was actually on.
Search conditions of carriage on their website.
Under the circumstances you have mentioned you should be able to seek compensation from Qantas.
From a technical standpoint, the conditions of carriage you agree to when making the booking do specify that QF are only contractually obligated to get you from A to B. Times and specific flight services do not form part of the contract.
They also reserve the right to oversell the flight, in which case providing you are at check-in on time you should be accommodated on their next available service. If those arrangements are not deemed acceptable by yourself then you are entitled to the 'denied boarding compensation policy' available on request.
I don't really know what that policy details.
You can argue the definitions at the beginning of the conditions of carriage imply our next service to be 'qantas, qantaslink and jetconnect' and by putting you on 3K/JQ they breached their contract with you.
Read over the terms of carriage and then contact customer care quoting the relevant sections they breached and you will probably get something from them.