In Argostoli and Lixouri, and in one or two smaller locations, you will find major Greek bank branches offering over-the-counter bank services. There are many cash machines and foreign money exchanges dotted around, particularly in tourist areas and larger villages. Post Offices generally have cash machines, there is also one at the airport. Credit Cards can be used almost everywhere so you can pay without withdrawing money, just double-check before you get to the cashier.