I own a 2011 Renault Grand Scenic with the 1.5-litre diesel engine. I was advised to change the cam belt as the mileage was over 80k and the car was five years old. I bought a cam belt kit and had it fitted by a local garage. Six weeks later, the belt slipped and caused massive damage to the engine. In fact, the camshaft sprocket has shattered.

As it was only six weeks, I assumed the warranty of the belt kit would pay the huge bill. However, the company that makes the kit has said it was fitted wrongly and reuse to honour the warranty. What should I do?