I just got a call from them too...when I asked them what credit card they were referring to they said "visa". I said Which Visa? Then they hung up. Definitely a scam
Play along with these people long enough to get some information as to who they are then post the name. You can usually find out the name of the business principle or the registered agent (attorney) for the company with a google search. Posting the name and phone number of either goes a long way to stopping the harassment. it is amazing how fast they stop.
Got a call from (626) 256-8683 and asked Google.com to identify the caller. Information found stated that the number belongs to ARS National Services which is a debt collection agency headquartered in Escondido, California, with offices in Jacksonville, Florida; and Phoenix, Arizona.