Northern Leasing Systems Sent a letter of demand New York New York

 I received a letter from Northern leasing systems on June 17, 2015. It is asking to paint outstanding balance of about $5200. Can't get a hold of anyone to return my phone calls but believing from what I've seen on the Internet that has to do with a credit card processing system. I purchased mine 20 years ago and my business foreclosed in 2010. There's no way I owe this. Let them take me to court. I bet it's not even my signature on any of their documents. You can't get blood out of a turnip anyway.