2009 CHEVROLET SILVERADO 2500 Structure Problems

I PURCHASED SOME AFTER-MARKET NERF/STEP BARS TO FIT MY NEW 2009 CHEVROLET SILVERADO 2500HD CREW CAB PICKUP. THE STEPS WERE INSTALLED ON FRIDAY 06/04/2010 ACCORDING TO THE MANUFACTURERS INSTRUCTIONS. THE STEPS WERE MADE BY DEE ZEE INC. OF DES MOINES, IA AND THE MODEL NUMBER OF THE PRODUCT IS 17053C. ON 06/06/2010 AT APPROXIMATELY 2230 HOURS, MY WIFE WAS PLACING A TWO YEAR OLD CHILD INTO HER CHILD SAFETY SEAT WHILE STANDING ON THE PLASTIC STEP AREA OF THE STEP BAR. THE PLASTIC STEP AREA BROKE FROM THE METAL STEP BAR, CAUSING MY WIFE TO FALL TO THE GROUND. ON HER WAY TO THE GROUND, BOTH OF MY WIFE'S UPPER SHINS OF HER LEGS STRUCK THE TRUCK FLOOR AND THE STEP BARS, CAUSING A LARGE AMOUNT OF BRUISING TO HER LEGS. I REMOVED THE STEP BARS THE NEXT DAY AND HAVE CONTACTED THE RETAILER FOR A RETURN AND REFUND OF...