Warranty claim rejected

My cambelt broke and messed up my engine and now when they have to pay out an amount of R25000 they are telling me it has been rejected cause I was supposed to check that the cambelt was changed...my question remains am I a mechanic to know what goes on in an engine and mind u my car was serviced on the 5th October by Bosch ( which they recommended) and never missed a service. The policy says that it pays for cambelt failure mind u....they got time to play