This topic comes up time and time again amongst punters on the poker tables and other betting auditoriums. (it doesn't affect me because 1. I have bigger bets on politics but I've given most back on sports bets and the horsies/dogs, so I'm not perceived as a threat to them and have held an account with WH and SB for 10 yrs plus).
There are some serious punters around the Treasury poker room who have been in your position several times. The consensus seems to be that BET365 will take you on (and not wind you back if you regularly collect) and Crownbet are also highly regarded. William Hill (Sportingbet & Centrebet), Luxbet and Sportsbet regularly recur as joke operators.
Legislatively, don't hold your breathe. In the queue ahead for the gov't seems to be curbing online gambling (esp. non-revenue sites), controlling live betting and gambling advertising. My wife is a solicitor and she used to work for MB; I can assure you they wouldn't go near a class action (nothing in it for them) S&G have too many bushfires to put out to be vaguely interested. The govt probably prefers if you were just a $20 punter to be honest.
So from my vantage point you seem stuck. I'd make list of of the Oz operators that you don't have n account with (if there are any) n ring them up before you open an account and se if you can establish a 'get set amount'. If you get a definitive amount from one or two you can use that to 'build upon' with the next one. Do a bit of shopping around and get the comparisons going. (?)
Or, become like me with smaller bets and not too successful, lol. All seem pretty clued up re spousal or relative accounts (the 87 yo pensioner having 5k bets sorta triggers their software alerts}. Swap sides and bid for WA TAB? (I notice it's dropped 60% to $250m....might be 2 or 3 in a few months?)
Overall though, on a serious note, I think you might find in the long run they all ban big consistent winners, it's just a matter of when.Good luck with it all, but multiple (as in every provider) accounts is the only way I think you can approach your dilemma.
.
