Toyota Kirloskar Motor Private Limited - Misleading for warranty of the vehcile

I have purchased a Toyota Innova Crysta Reg No - PB**C **** in year **** and purchased extended warranty of the vehicle for ****** Killometers. Now the Turbo hose pipe having leackage and company refused to replace it in warranty and they said plastic parts not covered under warranty and the time when we purchased the extended warranty no one convey about that and moreover its part of vehicle if company do not give a warranty of plastic part then why they use plastic in the vehicle and why they promote extended warranty.