Mate, it is the CBA and is something that only started in the last 8-9 months. Before that their exchange rate was terrible and they charged a fee for each transfer. They now give a better rate than OFX, usually about 0.2 baht below the XE mid rate.
My transfers are $20,000 when the AUD/THB rate is above 23-24 and $5-10,000 when I have to accept the current rates. If it ever gets to 24 again I will bring a lot more over as a gift to my wife.