Hi all as an occasional Thai / Bangkok traveller it was frustrating when Citi pulled out. However as per many forums the best way is to bring A$ with you to change there. The Superrich ones usually have the best reputations for best prices. Regularly I fly into Bangkok with A$ only. The green superrich right near the airport train (I usually catch it in to avoid traffic) has the best FX rates in Suvarnabhumi Airport. Don Mueang airport has HappyRich which is a lot tougher to find and recommend that you look at this video to find https://www.youtube.com/watch?v=IItVf4acb5I (I got lost trying to find it even with video).
Have usually been going to Green Superrich Head Office as close to Central World with FX differential usually 10-15pts. However recently stumbled across Yes Exchange which I have found the best with 8pts difference (eg today Buy 21.15 and sell 21.23) and noticed other Australians going there as well. Happy to hear other recommendations and always good to look up the FX before you go - websites below (make sure you look at specific branch). For clarity, there are no additional fees. Make sure to bring passport as some do not accept copies/soft copies driver licenses.
Yes Exchange https://yesexchangethailand.com/
Green Superrich https://www.superrichthailand.com/
Orange Superrich https://www.superrich1965.com/en
Happy Rich https://www.happyrich.co.th/Home/Rate
Geesus just bring Macquarie or ing debit bruh