Rear hatch area leaks!


Problem is I still have a leak in through the left side ventilation flap which is down below the left bumper line where it attaches to the car I have attached a pic of it.
Water fills all the slats of that thing up and comes in. Couldnt replicate it on the drivers side one for some reason.
Does anyone know the part number to replace it or is it something I need to pull the bumper and look at to see why its allowing water through the flaps?
Has anyone else had this one and how did you sort it?


