I have been receiving threatening calls from these peopl as well. They have sent e-mail letters to several of my work colleagues and they have been calling family members with the same last name as me.
They have yet to show me what I have contracted with them. They are a scam. They try and wear you down so you will pay. DO NOT PAY THEM. If they were legit, they would go the route of any law abiding collection agency. My calls are coming from someone calling themselves Nanzaz Smith. Like thats a real name.