PDM associates HELP

I got a disturbing call from PDM associates while I was at work telling me that I owed $350.00 on a loan from SSM, and that they were going to proceed in filing a motion for a judgement against me in the amount of $1400.00 including attorney's fees unless I paid them this month. The man identified himself as Darrin Meyers and said he could stop all of this from happening if I could pay him. When I asked for a debt validation letter he told me they could not provide me with one, that I had to call my bank and verify that the funds from SSM were sent to my account. I did default on a loan with SSM, but got an email saying the account had been sent to collections with AIS. ???? Not sure what to think. This guy made it sound like he was with an attorney's office. I told him I would call him back tomorrow, and he said he would put a 24 hour administrative hold on this and he would not contact the courts until tomorrow. Is this for real? Honestly what should I do here. I know I can't pay them the $350.00 in one lump sum. Any advice is appreciated. If it helps I live in Minnesota.