SAR and Associates review: Collection of an unpaid debt 2

I received a call on my cell phone this morning from Blaze Miller, of SAR and Associates a debt collection company, indicating that I owe money for a debt from 2012 in the amount of $450.00. He convinced me because he had my social security number, address, email address, and bank account. I set up 3 payments. He asked me what credit card I would be using and I indicated the same as I had been using which he didn't know. He indicated that he would send me a letter via email of the agreement we had made. During this time I was on the internet looking up SAR and Associates to find out they are a scam! He put his manager, Michael Owens, on the phone to try and convince me this is a legitimate company and they were sending me confirmation via email. I did get an email from them indicating the agreement was attached, but there was nothing. the email was just an email, not on company stationery. I asked for a confirmation and received nothing. I was told that I would be prosecuted if this was not paid. I want them to stop calling my cell phone and not to send me any more emails regarding this fraud.