Another data point.
ATM’s in VietNam usually (maybe always) charge a fee to withdraw, and often have a lowish maximum withdrawal limit.
Yesterday (Sunday) I used the ING card to withdraw VND3,000,000 (the maximum allowed) from an ACB branded ATM.
The ATM charged a VND55,000 fee.
At the time of the transaction XE.com showed an exchange rate of AUD1 = VND17,259.67.
So the theoretical cost (before fee) should be AUD173.82, and the fee should be AUD3.19, a total of AUD177.01.
What hit my ING account was AUD178.20.
Then, the next day (Monday), a fee rebate of AUD3.21 appeared.
So, I was charged a net AUD174.99 versus the theoretical AUD173.83 - a variance of AUD1.16, or 0.67%.
If this test is representative, it indicates that the fee rebate for VietNam ATMs is about right, and that the exchange rate applied is ‘fair’.