Goodyear Tyre — regarding issue of damaged tyre in skoda

I have purchased new skoda rapid from sagar autotech pvt. Ltd with goodyear tyres. Within 10 months and around 5000 km, my tyre got damaged by itself while running and finally i shown my tyre at service station, they said its not manufacturing defect. How come it is not manufacturing defect that tyre got damaged within 5000km when the manufacturer give warranty for 40000km. This shows the quality of the goodyear tyres. They forced me to buy the tyre with own money, but just reduction 30% of price. The price of tyre in the online shows to the price of the showroom price (After 30%). That's mean the goodyear warranty person still cheating the customer with the price. Please understand my issue and help me.