In my view OP's parents should view the total compensation offered as approx $3000. Few reasons,
1. The 'ex-gratia' payment at airport. This is definitely part of compensation.
For those who chose to wait till the next day to fly in the J cabin - their compensation is this $700 for arriving 24hrs later, plus hotels, food etc looked after
For the OPs parents, the compensation is $700 plus the fare difference by schedule (as returned at a later datE). This is not how QF staff at LAX described it at the time. QF themselves descrived this as an inconvenience fee, that was independant of any fare difference refund.
2. The 'additional' $500 voucher and 50k points. This was seemingly provided as part of a general discussion about the downgrade and behaviour of the agents at LAX (I assume). Now not many details have been provided about the actual behaviour of agents in LAX, but if QF gave $1000 value for each coughpy experience with an employee, I would be very rich, and they would be broke. Again I think most (if not all) of this payment is an overall payment by QF for the downgrade. I have provided many details about how my parents were treated. If you read QF's last response you will see that even they agreed my parents were treated appallingly and measures have been put in place to stop it happenting again. Also, voucher and point are only of value to my parents if the choose to fly QF again, which they don't. They would happily give up the voucher and points for the full fare difference refund. Anyway, my father paid for a Business Class ticket so why shouldn't he get the points for it?
I don't believe OP has published anything about what they actually paid. But looking at October 2015. Yes I have. They paid $15,000 for two return Business Class airfares to the States.
BNE-JFK return can be had for $8600 in J, and $2100 in Y (looking at cheapest fares)
So the difference is $6500 (Obviously different dates will give different results - but I suspect this is ballpark)
Now the OPs parents were downgraded for 13hrs out of a 36hr journey (one leg out of four) (ie 36% of total journey)
About $2350 applying this percentage to the fare difference.
So in this respect I would view the overall QF compensation as fair, albeit certainly not overgenerous. I wonder if you would feel the same way if it was your money they took? I certainly would not feel that I was treated fairly.--
I agree the downgraded fare table itself (1200/1250) is pretty poor, but I believe in all these situations that a payment at the airport is generally made, so in my mind this needs to be included as part of the overall package (and is potentially reflected in the table) (presumably QF also has rules about airport payments)
Where I think QF has let themselves down in this situation is:
a. Seemingly the agent behaviour at check-in
b. The communication with the OPs parents - seemingly not enough, and simple things like telling them how much the refund would be, and proactively quickening the refund process via Flight Centre, were not done
c. Not fully explaining why these pax were selected for downgrade (per OPs post they had checked in early and were SG members). RedRoo posted a generic statement but it didn't seem to answer the question
While some on this board also think the number of thread views should make QF more generous, I actually think it has the opposite effect. I suspect they are being very cautious here not to set a precedent. Possibly, but I think sometimes people need to make a stand. Otherwise many unfair practices that happened in the past would still continue today