affidavit processing

got a call from a marshall walker from affidavit processing out of jacksonville, florida. he says I owe money from a pay day loan back to 2005. he had all of my personal information bank, name, account number, etc and said I owe them $700. he has called several times and I asked for copies of what he was talking about as this was the first I heard I owed anything. said I was going to be charged in itasca county court where I live for a worthless check issued. I gave him my fax number so I could get a copy of what he was talking about as I told him that this was the first I have heard of all of this. he said they are not legally responsible for having to tell me anything or send me anything as I gave up that right when i got the loan. first of all, why would they wait until now to get money from me when I have no recollection of this loan. secondly I gave them my fax number so he could fax me what he called a "validation letter" we have had the same fax number for years and he called me back and accused me of being a liar and being in serious jeoparady of not cooperating. I then gave him my email address and I still have not received anything. he is now calling me and asking me to transfer him to human resources of where I work. what should I do??? help? is this guy legitimate? what should I be asking him to make sure it is legitimate