You are told that they have spotted an unusual transaction on your account for £250 and ask if you made it. When you say No, they then ask you to confirm that you still have the card by asking you to confirm the 3 digit security code on the back of the card.
This is a confidence fraud and you will not realise anything has happened until you get your next statement and several large internet purchases have been made at your expense!!
This happened to a local head teacher in the Exeter area very recently.
Be careful out there