You need to be a bit careful. In the UK, where chip & PIN is well established, this type of unauth transaction claim is common. However, if the PIN was used, then banks only reverse the transaction in exceptional circumstances (e.g. they are able to trace back multiple fraudulent transactions to a specific terminal) - in the vast majority of claims, they successfully argue that the cardholder was negligent in not protecting their PIN, as there would be no other way for a thief to find it.
The key issue is that the bank, and most courts, will assume that the customer was negligent with the PIN in the absence of strong evidence to the contrary