I actually had the same problem, I was so out of it that I confirmed the zip code. I've cancelled my card, but I was hoping you could tell me how you dealt with the problem, since your post was made about a year ago I thought you might be able to help.
Received a call on my cell from this "Vista Services" telling me I was being offered a discount on gas due to the credit card account I had with them and they just needed to confirm my details as they related to a credit card ending in the four digits they provided. I advised I did not have an account with a "Vista Services" and the guy then changed his story to "you purchased product with your credit card ending in XXXX and we just need to confirm you mailing address." The numbers on the card he provided were from a card that had been lost and cancelled several years ago, thus I knew it was a scam. I alerted my bank/card provider.