They called and left me a message about possible fraud on my Barclay with itunes reward card. I called the same number back and only after giving them my information, I then questioned whether it was a valid Barclay call. I then called Barclay's customer service to verify, and it was in fact a call from their company.

Call was from Barclays Bank Visa fraud protection group. Seemed to be legit. They notified me of an unauthorized charge

This is a fraud protection system for barclay online transactions.

It's Barclay.  Called as soon as I ordered from Apple Store.  Didn't answer then went directly to my Barclay account online.  There was a fraud protection alert waiting for me.  I had made a few purchases that day, so I believe they were just looking out for my best interest.

YES I TOO HAVE GOOTEN CALLS FOR  A USE OF A VISA THAT IS NOT EVEN MINE
SO HOW IS IT THAT THEY CAN APPROVE IT WITHOUT HAVING SOMEONE TO TALK TO LEGITE.
I THINK FRAUD IS INVOLVED
I WOULD NOT TRUST IT

I concur with Faithman.  Just made an internet purchase with my Barclays Visa and got a call within minutes of transaction.  Fraud protection contacted me to get an authorization for the purchase.  I don't get this with every single transaction, but have with certain online purchases.