Want to find an ATM that will dispense more than 300 euros at a time.
Try ones located on banks.
Typically its not the ATM but your bank account. However, in Germany I had trouble with an ATM that limited me to less than my bank's limit - it was inside a bank and oddly enough when I tried the ATM next to it I was able to withdraw my requested amount with no problems.
On our recent trip, I found that the max amount available on the ATM, was the max amount I could withdraw, regardless of my bank's limit. When I needed more euros, I would use another bank's ATM card. I have several different bank ATM cards.
We just spent 3 weeks in France using exclusively bank ATM's, and did not find an ATM that would dispense more than 300 euros at a time. So we both took out 300 euros every day or so and kept them in RS money belts & neck pouches.