My five year old 56,000 mile Porsche C4S recently had a routine service at the local official Porsche centre, where it has always been serviced. In the course of replacing spark plugs, a heat shield needed to be removed from the exhaust. A technician sheared off a bolt attaching the heat shield. The dealer denied responsibility and blamed the age of the vehicle and corrosion. The engine will need to be removed to drill out and replace the bolt, at an estimated cost of over £1,500. In addition the dealer will not rule out further cost being incurred in this process. What is my legal position in this matter?