Bad service - Oven temperature too high

Good morning I bought Elba 90cm gas electric stove at builders before I was using defy stove and it was not giving me problems I wanted a bigger oven because I love baking . Since I bought it am not happy at all whenever I bake it burns my cakes and everything the temperature is too high it need to be adjusted. I sent an email to elba they never bothered to call me or help me with my problem I regret waisting too much money on this stove am not happy at all. I wish someone can just assist me with this cause I believe is still under warranty.