Yup,
That tends to be the problem with mecchys in a big garage such as a Renault Dealership.
They dont care about the job really, because they are getting paid the same no matter what.
Its sh*te.
You should walk into your dealership, and demand that you have the problem fixed.
Demand a sheet invoice telling them exactly what the problem is, and how it was fixed for your records and inform them that you will be seeking legal advice if this problem should happen in the near future again.
If they cannot do that, then you are well within your rights to demand a replacement car of the exact specification, providing it is NOT altered from the manufactures specs and older that your original vehicle.
If you tell them that, and be authoritive, with a firm tone, and cool attitude, you will most definitley have them by the balls.
Let me know mate.
Downie