usa fast cash this company keeps harassing me at work with phone calls saying I owe them money and threaten to take legal action and I will not give them anything , Internet

I received a phone call today from a weird # 000-000-0000.  Did not answer the phone.  The person (Mike) left a message very thick accent telling me that I had an outtanding loan of $640. I have been paying this loan since Feb.  I paid close to $5,000 to different companies.  I called them back to find out who I owed this loan too and little to be known I have paid $1,496 Cash Advance.  They told me that if I did not pay it that they were going to come to my home and arrest me.  I am not making anymore payments because I feel I have been scammed.