aroa;
Take CASA out of the frame altogether.
Letter to Senator, the Hon Penny Wong, Minister for Finance and Deregulation. Put the government on notice of your legal intents but leave the door open that you may be willing to accept an ex gratia or Act of Grace Payment in lieu of taking the matter further. Include an accrual of interest component and stipulate a reasonable time frame for a response. (Copy of course to Bob Katter).
Nature mostly takes the easiest course. They may admit to a "perceived" injustice.
There is also The Public Interest and Test case Scheme you can avail yourself to via the Lawlink website. A good and funded case may get you a Barrister of the quality of Langmead.
PM me if you want help.
Cheers.