Quest Diagnostics Unscrupulos collection procedures, Internet

After almost 2 years, I was contacted by a collection agency for Quest diagnostics claiming I had an unpaid balance from January 2008.  At the time, I was covered by 2 insurance plans and would have submitted the unpaid charges if they had billed me.  The collection letter said Quest attempted to collect these charges and were unable to reach me.  I have lived at the same address almost 22 years.  If the collection agency could reach me here, why couldn't Quest?  Now it is too late to submit these charges to the secondary insurance.  My parents paid the bill today.  This is really unscrupulous because they use scare tactics by referring unpaid bills out to collection even though they themselves never made any attempt to collect the bill.