I just bought a KitchenAid oven which, has both convection and conventional settings with a convection conversion setting. I have been baking for over 40 years, and nothing I have made in this oven is edible. I am using the conventional feature (as with a typical conventional oven) to make breads, quick breads, cheesecake, etc. I have had 5 technicians out who say that my temperature is correct. They have calibrated the temp up and calibrated it down. Nothing works. I have had to increase the baking time on the recipe by double (or longer), and at times, I still have raw liquid dough in the center. I am not doing anything differently from the 40+ years of baking these recipes. What is the problem and how do I fix it? 
The first thing to do is buy an oven thermometer to see what temperature your oven actually is. Technicians have no real way of knowing what the temperature is when you are using it; what you need is hard data. Oven thermometers are very cheap, and it will give you a better idea of what's going on. Put one in your oven and then turn it to the temperature you want, then see what temperature it actually gets to. Next, read your oven's manual thoroughly to make sure there's not something you're missing. One of my ovens wasn't working--I set the temperature and mode but it wouldn't heat. I thought it was broken before I figured out it wouldn't work if the clock's time wasn't set. Don't ask me why it was designed that way, it doesn't make sense but there it is. Some ovens have a start button and won't change the temperature unless you press it. 