How do you stop a Renault bottom door sill taking in water problem of water in the door swishing about?

There is a drain hole at the bottom of the door that gets blocked. If you pull the seal off the bottom of the door near the end of the door furthest away from the hinge and run your hand along the bottom of the door you should be able to locate it and remove the blockage. You may need something like a screwdriver to poke in depending on how badly blocked it is.