Anytime anyone calls saying they are calling from the bank .. always find out which bank .. credit card ending in which 4 numbers .. get their name, phone number and extension and offer to call them right back.
Then call the number on the back of your credit card .. verify that their fraud department (or whoever) is trying to contact you .. give them the name and extension of the person you just spoke to .. and if it was a legitimate phone call you will be able to get through to the person who is trying to reach you and resume your conversation from there.
If it was NOT a legitimate call .. then .. end of story!
NEVER talk to anyone who has initiated the phone call from their end!
Make sure the call is initiated from YOUR end.