Copper AT3 LT tyres and fake warranty

Used Cooper tyres at3 LT before and got Over 140000kms on them with no problems. Bought another set of 4 and after about 30000klms a year and 4 months after having them fitted one started a side wall crack just under the rim only on one side. Was told when fitting the new tyres that you get a 5 year warranty. Ya whatever! Cooper rejected my claim with such bs excuses. Such as under inflation or overloading or impact. The tyre is load rated for 1800kgs. And the most I loaded is about 7 to 800 kgs never had a flat nor went off road as it's a not a 4x4. Cracks are in a weird place and only on one side of the side wall just under the rim. Don't get ripped off with this product. I also got 4 more opinions from 4 other well known tyres fitment centre's and they all said its a manufacturer defect! It seems like Cooper tyres is not what it used to be!