They said it was because the item was not faulty, but probably damaged by a stone or something coming in through the grill. I would say that a) that is unlikely b) it should withstand anything like that in the normal way of events (I only drive on normal roads and I'm very careful). I anyway only have their word for it. I would argue that an 18 month old Renault should not be suffering from wear and tear damage after only eighteen months.
I am taking it back to the original garage, where I leased, it next week. If they also refuse to repair it under warranty, do I have any redress under common law? If so what should be the best procedure? Financial ombudsman?