Universal Premium Iconnectdata Late posting of checks mailed to them Charlotte North Carolina

This company was not posting checks received until several days after late charges would be assessed. I mailed my payment eight days before the due date from Mass. to NC. It was posted TWELVE days later. I was assessed an outrageous late charge which I fought. They waived the late charge. The next bill, that same thing happened. I am still waiting for a call from a supervisor. I now send all payments by USPS Certified. Funny thing, they all get to NC in 3 days.  I have not paid the second late charge and they have done nothing about it. This would be a good company for a class action suit!