I have read it now and yes you are right - under the terms and conditions they won't give you the refund until after the plane has departed, so even if they recognised now that they owed the money they wouldn't refund it.
Just amazing how badly passengers are treated by airlines - they can take your seat away from you that you have paid for and you have no right to get the money back for possibly many months! Wish I could have run a business like this! (Well no I don't because I believed in ethical practices!)
Here's a general but hypothetical situation:
Lets say you order a car for $25K and the option for leather seats is an extra $2K so you tick the option box on the form and pay a total of $27K. Delivery is scheduled in a few months time. Then the car dealer says that it can't provide leather seats as it has run out of cows/sold them to other customers or whatever. Then the car dealer say that they will only refund you the $2K once the car arrives without leather seats and only when you accept delivery, the dealer claims that they have "lost" the receipt for the payment you made for leather seats, but reassures you that they will refund you the $2K because they are such trustworthy guys.
What would you do? What would be the finding and consequences of this dispute going to a consumer law body?
Going back to the OP's situation though,if its true that they were told that all the available exit row seats were all "taken" (brought for cash or allocated? irrelevant as they're all factors within QF's control) - maybe go in a do a dummy booking and just see if QF are still selling exit row seats for the flight that you are now booked on? If they are still selling exit row seats then screen-shot that, and you can add misleading and deceptive conduct in addition to refusing to provide a refund for goods and services not provided, if the OP does want to (or may need to in the future) go down that route. That might get their attention.
I guess the OP has a few options and hasn't yet indicated which way they will go, depending on how important the exit row seats were to them and how much of a fuss they want to make, all the way from the "path of least resistance" through to a time consuming personal crusade.
1. Accept it a hope that the refund automatically/magically happens.
2. Accept it and pursue the refund after the flight is taken.
3. Complain and try to get Qantas to fix it using the HUCA method.
4. Complain and try to escalate internally with Qantas now (tried and didn't seem to work for them).
5. Take it up with some external agency or consumer affairs body (airline consumer advocate or Dept of Consumer Affairs in their own state).
6. Do a big social media campaign and hope that it gets "noisy" or enough publicity to prompt Qantas into action i.e. the Facebook/Twitter approach.
7. Try the credit card chargeback for goods and services not provided (risks the original booking, original credit card and may require alternative airline bookings that may be more expensive now).
Any others I have forgotten? I bet that I have.
Complaining about it here on a specialized frequent flyer web site is another option but the whole point of this is to hopefully elicit help or advice about effective ways of getting the problem fixed that the OP may not have known about or considered, but its their choice at the end of the day as its their bum in that seat...