The following was taken from a post on Facebook and edited for better understanding.
This information is worth reading. By understanding how VISA & MasterCard Telephone Credit Card Scam works, you'll be better prepared to protect yourself.
One of our employees was called on Wednesday from "VISA", and I was called on Thursday from "MasterCard". Note, the callers do not ask for your card number; they already have it.
The scam works like this:
The person calling says, "This is (name), and I'm calling from the Security and Fraud Department at VISA. My Badge number is 12460. Your card has been flagged for an unusual purchase pattern, and I'm calling to verify. This would be on your VISA card that was issued by (name of bank). Did you purchase an Anti-Telemarketing Device for £249.99 from a Marketing company based in (name of any town or city)?"
When you say "No" the caller continues with, "Then we will be issuing a credit to your account. This is a company we have been watching and the charges range from £150 to £249, just under the £250 purchase pattern that flags most cards. Before your next statement, the credit will be sent to (gives you your address), is that correct?"
You say "yes". The caller continues - "I will be starting a Fraud investigation. If you have any questions, you should call the 0800 number listed on the back of your card and ask for Security. You will need to refer to this Control Number. The caller then gives you a 6 digit number. "Do you need me to read it again?"
Here's the IMPORTANT part on how the scam works. The caller then says, "I need to verify you are in possession of your card". He'll ask you to "turn your card over and look for some numbers". There are 7 numbers; the first 4 are part of your card number, the next 3 are the security Numbers that verify you are the possessor of the card. These are the numbers you sometimes use to make Internet purchases to prove you have the card. The caller will ask you to read the 3 numbers to him.
After you tell the caller the 3 numbers, he'll say, "That is correct, I just needed to verify that the card has not been lost or stolen, and that you still have your card. Do you have any other questions?" After you say No, the caller then thanks you and states, "Don't hesitate to call back; if you do", and hangs up. You actually say very little, and they never ask for or tell you the Card number. But after we were called on Wednesday, we called back within 20 minutes to ask a question. Are we glad we did! The REAL VISA Security Department told us it was a scam and in the last 15 minutes a new purchase of £249.99 was charged to our card.
Long story made short - we made a real fraud report and closed the VISA account. VISA is reissuing us a new number. What the scammers want is the 3-digit PIN number on the back of the card. Don't give it to them. Instead, tell them you'll call VISA or Master card directly for verification of their conversation. The real VISA told us that they will never ask for anything on the card as they already know the information since they issued the card! If you give the scammers your 3 Digit PIN you think you're receiving a credit. However, by the time you get your statement you'll see charges for purchases you didn't make, and by then it's almost to late and/or more difficult to actually file a fraud report.
What makes this more remarkable is that on Thursday, I got a call from a "Jason Richardson of MasterCard" with a word-for-word repeat of the VISA scam. This time I didn't let him finish. I hung up! We filed a police report, as instructed by VISA. The police said they are taking several of these reports daily! They also urged us to tell everybody we know that this scam is happening.
Please pass this on to all your family and friends. By informing each other, we protect each other.