I once punched in a 5,000 baht withdrawal at a Krung Thai Bank ATM inside a Tesco Lotus store in another province but received only three or four thousand baht in cash (it was years ago). I went to the Lotus customer service counter, who said it had happened before with that machine. They called KTB for me and my account was credited by the bank. In this light, never go ahead with an ATM withdrawal if the machine warns you that it is out of paper and cannot issue a receipt.