Mechanical Warranty valid claim declined

I took an extended mechanical warranty with dotsure. My clutch went due to wear and tear. When I claimed for the replacement of both the clutch and flywheel, they declined based on the statement that they only cover mechanical failure and not wear and tear. My question to them was, how else does a clutch fail if not due to wear and tear? Secondly why did they have on the list of items covered by the plan? I got no answer, lucky enough I had Hollard insurance who paid for the claim real fast and the car was repaired.