All of the bank (not credit union) ATMs in Melaque should work (Banamex, Intercam/Kapital, Azteca, BBVA). They all have varying charges (I think BBVA is the highest) and always make sure you decline the bank’s exchange rate in favor of your home bank’s rate. The ATM in LM works for some cards but their fee is high and sometimes the withdrawal limit Is low. Depending on your card’s daily limit and the bank’s limit, you should be able to withdraw 8k to 10k pesos from a Melaque bank.