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.
I would appreciate it if my number was erased from this annoying number list...... They call at all hours of the day..... Two,three and four times...... Don't leave a message if cant get to the phone.....
This is definitely a telemarketer, scammer, or perhaps a phisher, who uses the final four digits to appear to be Customer Service at your credit card company. Those digits, of course, appear on bills, receipts, even mailings, and are easy to obtain if you are dishonest enough to steal.
A nice touch is to have Customer Service as the caller's ID! Avoid these guys.
These jerks called me yesterday at about the same time. They are offering free gasoline in return for a charge of $2.95. This is pretty clearly a phishing operation. BEWARE!