Received this from a Friend today,(new scam)

Phone call from Mastercard or Visa etc., saying your card is being used fraudulently its a scam-they end up asking you for your 3 digit security number on the back of your card then steal money from your account.
Hang up and phone your Credit Card Company or the Police-loads of people have been caught out.

Thanks for the warning

I'm surprised they can do this, when I worked for a well known insurance company, the organisation that did all the credit card processing never actually used the security code to verify the card/card holder. The question was asked to see how confident the caller was, if they ummed and ahhhed then suspicion would be roused. So you could actually give ANY three digit number as long as you sounded like you meant it!
However, I think most of us realise that any unsolicited call or email in connection with an account is probably dodgy. I get emails regarding accounts with banks I have never dealt with - how stupid do they think I am????