Defy sells broken ovens

I bought a brand new Defy stove Slimline1 - ZULU: ********** ********** 436711 at game Cresta. The stove keep on tripping the electricity. A Defy technician has now been sent out twice, without resolving the problem. I now want either my money back or a brand new stove, but Defy keeps on sending a technician to fix an oven that was opbviously broken when I bought it the first time.

Defy - please give me a brand new oven, or give me my money back. Do not sell broken ovens to your clients and then send technicians out to come and fix it. Unacceptable