Recovery for what?

I received a voice message at work today from a Mrs.McGary and she said that I had a debt and they were going to garnish my wages. I called the number she left 877-601-5871 and spoke to Dr. Garza. He said I had received a direct deposit loan from PayDay loans and when they tried to collect direct from my checking account that either the account had been closed or I had stopped payment. He also said that information had been sent to my house and retuned by mail. I never did receive a loan from this company,I have had the same banking account for the last 10 years and also have lived in the same place for the last 10 years and have never returned mail. I asked Mr Garza to give me more information on the alledged loan and was told several differnt vague dates. I offered to get bank statements as proof, if he would tell me what when they supposedly loaned me the money. He said he would send me information on what I needed to get to him. I called back to verify if he was going to mail or e-mail me something and he said he e-mailed it but I didn't get anything. He said he would re-mail after verifying my e-mail address. After about 1/2 hour I received a settlement agreement to sign and agree to pay in 2 days $300.00 as opposed to the $1,008 that I owed them.
I really don't understand how they can garnish my wages just upon their word that they gave me money.
SUGGESTIONS?