My 01 330i Sport seat is starting to look a little tired, especially on the part next to the door. When I take the seat belt off it tends to get caught on the side support and has worn the leather. The seats are black, but where it has worn it is loosing its colour. I use leather care cream treatment to stop the seats cracking, which has worked, but the wear from the seat belt is starting to annoy me. Does anyone know how to touch the leather up? Put the black back into the leather??