Thanks Pat, appreciated.
If that's the case with your car, you will need to lightly sand the scuff as smooth as possible, and feather it in to the existing painted trim.
Then, using a light scotchpad, key the surface of the entire trim panel.
If it cannot be easily removed, just mask off around it, and lightly spray a few coats of plastic primer (grey would probably be the correct one for your car), and once fully-dry, apply a few light-medium coats of this http://www.ebay.co.uk/sch/i.html?_nkw=renault+trim+paint&_sacat=0&Transmissi on=Manual|!&_sop=3&LH_Price=..1%2C000%40c&_dmpt=Au tomobiles_UK&_odkw=a+class&_osacat=9801&_trksid=p3 286.c0.m270.l1313
again, allow to fully dry, then a couple of light dustings with some clear lacquer (this time using a heatgun or hairdrier to fuse the finish), apply the coats until you get a finish which matches the rest of the car, bearing in mind that more lacquer will move the finish from Matt to Satin to Gloss.
If you can work in a garage, all the better, as the area must be kept dry whilst the paint is wet. Also, take your time, as a well-executed job will be a source of pride, whereas a rushed job will be a constant reminder for you to kick yourself.
If this sounds daunting, it may be worthwhile getting a few quotes from local smart repairers, just for comparison. You could probably do it yourself for circa £30.