I have a Polo 1.4 Match that is just inside its warranty period and has done about 28,000 miles. The clutch is slipping and needs replacing. The Volkswagen garage says this is normal wear and tear and is not covered by the warranty unless the flywheel is damaged, which it isn't and therefore I must pay £750 to fix it. Is this correct? Surely a clutch should not go as quickly as this?