I purchased a new Citroen C4 Cool edition in July 2007. It was due its first service in July for 2 year's use or 20,000 miles. I had only done 10,000 miles but the service went ahead at a Citroen garage. Prior to the service I noticed that my back discs were rutted with deep gouges in them. I asked the garage to look at them and questioned why this could have happened when the car has done so few miles. They thought underuse may be a reason. They advised replacement but said it would not be covered by the warranty because this was classed as wear and tear. Can you help?