My car, a Citroen C4 1.6 HDI, broke down with a very loud cracking noise from under the bonnet. The franchised dealer found the alternator drive belt was breaking up due to road grit ingress and the noise was due to a strand from the disintegrating belt slapping other components. They showed me a picture they took of a sizeable quantity of road grit found on the engine undertray and embedded in the belt. An A-road near here had been resurfaced recently with grit on tar. I had to pay the repair bill myself, not a massive sum, but the car is under guarantee and I maintain that inadequate screening, that allows road grit to get to an auxiliary belt, is a design fault. This is typical of Citroen's reputation for customer goodwill. Have you any thoughts on this episode and heard of this type of fault before?