Think that might have been me.
My wheel bolts rusted like yours after only a few months. Complained to the garage and they blamed me (IE. must have used something like an acid based wheel cleaner ... which I had not). Contacted Renault Customer Support and in the end got a voucher for £100 that I could use against a service etc. as compensation. In the end I bought some TPI polarized bolts for the car (about £50 I seem to remember).
Basically... the bolts are very poor quality (just cheap Zinc plating by the look of it!). Even the four that had been removed when the locking wheel nuts had been added and hence never really used (just in a bag in the glove box) had slight rusting on them. Just a bit of cheap penny pinching by Renault.
Not got the car any longer and the wheel bolts on my new Focus ST3 are really nice (decent chrome on them) and hard as nails.
PS. Here you go:
http://www.clio197.net/forum/showthread.php?46751-Rusty-nuts!-200t&highlight=rusty