This could be an issue within the winder motor [unrepairable and expensive to replace] or a fault in the door pillar connection which can get wet and therefore corrodes. As it's part of the wiring loom it can be a bit of a pig to replace!
You may be able to clean up the connection and use something like WD40 to help repell moisture. Once you have a working connection i'd be inclined to put some sort of sealant over the joint if I could, not Petroleum Jelly as it'll rot the rubber.. maybe some silicon bathroom sealant. Don't be too heavy handed with it because if the elecrical connection is disturbed during the job it's a right pain to clear the solidified gel out!
If you want to have a go yourself, have a good think about the job and possible ramifications of these suggestions, otherwise pop down to your local Independant Renault Specialist rather than main dealer. Actually, any good mechanic should be able to help out.
Terry [same prob, passenger door!]
July 2007