Did you take it to a Local (Non Dealer) Renault specialist they usually know all the tricks
Why not try a local motor factors? There are many, many, aftermarket parts available at a fraction of the Dealer prices, I find it difficult to understand how they can justify those prices except they are STUPID enough to get rippedoff in the extreme?
Or Try www.gsfcarparts.co.uk
who will work mail order and www.eurocarparts.com
Best of luck