You can order a special spray paint at your Renault dealer for this, they use it themselves in the garage for fixing damaged cars. It's especially for painting plastic parts and in the correct color.
I've used it to respray the grey plastic door parts and their brand new now. If your repainting them, you should take them of the door, use very light sanding paper and then repaint the whole part to avoid colour difference when paiting only a small part
Order number at Renault is 77.11.238.903 and it says "BB Pierre 205139". Costs €19,-
Good luck!

