Defy bad service

We bought a Defy oven from Hirsch in 2018, and the inside glass exploded about 3 weeks ago whilst cooking. After many many calls to Defy thay send a technician out to come and investigate. Tech then ordered new glass without giving explanation of why the inside glass exploded.. It's been 3 weeks and I have been making call after call to defy, with empty promises from the service Centre.. Managers is always busy and no one calls back or answers the phone. I'm so frustrated and would seriously consider other products next time.. The technician that attended to the service call is missing in action and does not even respond to my calls or whatspp.. You a disgrace defy.