Game gateway blames defy for defection

I purchased a glass top hob in December It was the last unit , I had a friend collect the item from warehouse the unit was unchecked on collection When I received it there was a slight dent on the glass . Too small to really notice

About 6 weeks after use the Crack started spreading. I've been trying to contact game gateway for 3 weeks to no avail.

I got response from them after I called the call centre and laid a complaint. Now they say they don't cover cracks. Then they blame defy and take no responsibility.