National Credit Adjusters National Credit Adjusters try to collect on a payday loan I have no idea about? Hutchinson Kansas

Today I received a letter from National Credit Adjusters on information I that I requested from them on April 15, 2008. I requested from them validation of this debt I have no idea about. They say I had a payday loan from mycashnow.com. I have never had a payday loan.
In this letter they say I owe $1489.56 on a $600.00 payday loand?

Secondly, they sent me some contract with no signature on it and it says that it is a promissory note agreeing to pay $743.64. Where this is coming from I have no idea?
On the second page it says that by clicking "I agree" below that I certify all of the information provided above is true, complete and correct and provided to us. It goes on to state I agree to terms and conditons, etc. etc. etc.

At the bottom it has my name with no signature at all.
I have already sent to National Credit Adjusters validation of this debt and this is what they have sent to me. What do I do from here?
Any help would be greatly appreciated.

cpcdman
mashpee, Massachusetts
U.S.A.