Complaint Review: Commonwealth Financial Systems NCC

April 2010, I started receiving phone calls from a collection agency, by the name of Commonwealth Financial Systems, NCC. The nature of their calls were an attempt to collect on an emergency room bill from 2006.  I requested that they send me what information they had from the hospital, stating I have an outstanding balance.  I never received anything, only a letter from Commonwealth stating I owe them money.  My information on the envelope was hand written, strange.  I later contacted Florida Emergency Physicians. They had no record or information on an outstanding bill.  They also informed me that, they do not sell debts to Commonwealth Financial Systems, nor has never heard of them.  I contacted Commonwealth Financial Systems and requested more information.  They hold me they didn't have to give me anything and if I didn't pay it, the debt would be given to another collection agency.  Is this how it really works?  An attempt to collect after 4 years, "STRANGE".