I have a new Bush G90SW. The oven is not working properly. It burns food at bottom and does not brown on top. Useless for making bread or cakes and everything else needs turning constantly. Engineer says not faulty it is designed that way as hasn't got fan at back. Argos won't change it. Why do they sell these ovens? I didn't know different types of ovens existed. What can I do? This oven is no good. Can I push for exchange under trade descriptions act?