I am mystified as to why the clutch plate from an air conditioning compressor has become detached on my 2001 Skoda Octavia. The clutch plate was found in the engine well at the car's yearly servicing. The only suggestion that the Skoda dealer came up with was to replace the complete unit at a cost of £600 plus labour costs. They did say that replacing the plate with a new nut and shims was not an available option. Should I get an independent garage to replace the nut and shims?