Don't bother with stressing and letting the local dealership spend more and more money. Go straight to
Renault Customer Services
(Manager Alex Phelan) and get someone to provide you with a car first. Then talk about the bill with them (You do not owe money for things that have wrongly been replaced) and I'm sure they will help.
The fault I would assume is not yours through misue / lack of servicing (Whether or not the vehicle is in warranty is irrelevant). Insist that Renault UK send one of their techs to the local dealer to evaluate the problem properly.
Sometimes you have to go to the top to get these things sorted.
If you want a full set of Renault UK director's email addresses let me know and I would be happy to oblige.