this phone number I did not recognize they said that they were from some kind of collection agency first they wanted my checking account card number and when I didn't want to give that to them they wanted me to go out and buy a prepaid card in order to make a payment and at that time I had refused to do eather. And they keep calling me and I don't answer the phone.

Are they still calling you and did they threaten to take you to court

This number keeps calling me. Called my stepfather and my ex mother in law. They say I am negligent on a pay day loan, which I've never had one.
They are threatening to to serve me with papers. Has anyone else been served??

Have you reached a resolution?

This is a well known extortion scam. You are most likely being called by foreign 3rd world criminals trying to collect on nonexistent loans. The fact that they threatened you is proof it's a scam. Show me the paperwork! Send me proof by US Mail (not fax, text, email, voicemail, or Mumbai Mule) Remember one VERY important fact: A debt is a civil matter, not criminal. Plus, court cases are a matter of public record. A call to your County/City/State court officer would tell you if there are any pending cases in you name. There won't be.