TL*THE CONTACT OWNS A GRACO CARGO 8D10CCE (NA). THE CONTACT STATED THAT HER CHILD COMPLAINED OF BACK PAIN WHEN SEATED IN THE SAFETY SEAT. THE SEAT WAS POSITIONED IN THE REAR DRIVER SIDE OF THE VEHICLE. THE CONTACT INSPECTED THE CHILD'S BACK AND NOTICED LARGE BLACK AND BLUE BRUISES. THE CONTACT STATED THAT THE BACKING OF THE SEAT WAS MADE OF GRATES WITH INADEQUATE PADDING. SHE CALLED GRACO AND WAS INFORMED TO RETURN THE SAFETY SEAT. THE FAILURE TYPE WAS UNKNOWN.