ATM Access Denied

When withdrawing from an ATM, how many times can you try to withdraw money? We have tried to withdraw from an ATM twice but it rejected us! Scared to try same machine or another ATM!

Is it 3 times per ATM or 3 times in any 24 hr period before the ATM swallows your card?!!!

We are in Vietnam and struggling to get cash unless we physically go into a bank.