Bridgestone Tyres India — both rear tyres worn out within 1.2 years of purchase of new suv creta

Address: New Delhi, Delhi

I bought new suv creta from hans hyundai, moti nagar, delhi. Within 1.2 years both the rear tyres have developed cracks. Car dealer refused to do anything and sent us to bridgestone select galaxy motors, tilak nagar, where the engineer examined the tyres and said that the cracks, localized rupture and denied any further help as it is not a manufacturing defect.
1. How come both tyres rupture simultaneously?
2. The suv has just completed 1.2 years and 25000km, and both rear tyres gone. Earlier we have drived other cars also on the same roads and never faced such problem.
3. The engineer is trying to put all the blame on us and trying to save himself from any help or compensation.
We want to replace the worn out tyres as these are still under warranty peroid and the company is totally denying. What further step should we take?