Defy game

I'm Mr Willemse, On November 1, 2018, I bought a Defy Gemini Petit stove with a glass top (hob) at Game in Kolonade Pretoria. 4 months after purchase, the glass top (hob) cracked from side to side without any reason. Problem was reported at Game, after which a Defy technician came to visit me to investigate the problem. His finding was that the glass top (hob) cracked by itself , nothing else was the cause of the crack, in other words a factory error. According to Defy and Game, the glass is not covered by the warranty, whereby Defy expects me to pay for the repair costs after I already paid R12496 when buying the stove. Not Defy or Game wants to take the onus on them. I suggested to Defy that the broken hob must been replace with a new one but they keep on saying that the glass top (hob) is not covered by the warranty. There is currently a 3 year warranty on the product at game, I took out an extended warranty up to 5 years. At the rear of the game's receipt slip is the next 'Guaranteed service on every product sold' We will have any item under warranty, repaired for you. According to this, Game is responsible for the replacement. What now??????