OP - there are a lot of half-truths and misunderstandings posted here.
If your card was used at an ATM then someone has skimmed your card at a terminal, and either had a camera looking at the pin pad, or had modified a pin pad that you used to record the pin.

If you really want to know where it happened then by looking at past transactions you've made you might be able to work it out.

In truth though, it really doesn't matter how / where it happened. You didn't make the transaction, so as long as you fill in any forms you're asked to, then you'll see the amounts refunded.

I've got around 10 years experience in this field, so know what I'm talking about! (my username might give that away too)

Don't worry about it - just comply with any requests from the card issuer.