If their calling about a credit card account, then I would look into your credit report just to be sure no one got a credit card in your name. And if your credit is good then these people are just trying to get money from you. And they'll go as far as threatening you with arrest warrants, etc. I would report them to the FTC and block the number. And never speak to them again! Talking to them and arguing about it just makes them wanna call you even more!