Ripping Customers off

I did purchase two tyres at GOOD HOPE TYRES last year the tyre had an open crack on the inside of the wheel and it is front tyres which is dangerous when anything can happened due to the nature of the problem that the people that work for GOOD-HOPE TYRES they just there to make a fast bug , and treat their customers in an unfair manner the proof of payment state that the tyres is guaranteed for two years it has not been two years or a year it is six months when this problem occur. I paid a lot of money for such **** service. PLEASE HELP I DON'T KNOW WHAT TO DO!!!