Microwave ok, Convection oven is useless

I started the search for a new micro after our old one finally died. Going to many stores and web surfing for features and prices the saleman at the local home store suggested the micro convection oven for baking small iems or pizzas. This sounded like a good idea except for price which went up dramatically for a convection oven. I finally narrowed down my list to the GE and bit the big one of price. Installation was not bad but I had put these over counter micro's in before. This one was larger than I realized after I got it in. Sticks out over the range more than my last. Getting used to the knob control takes some time but not bad.This micro has good power as a microwave and features most high end units have. I like the machine ok except for the feature that I spent all that extra money for .."CONVECTION OVEN". I thought this is perfect for baking because of circulating the heated air and a small space would heat up quick and be more ecconomical than our range oven. Wow was I surprised. It took 15 minutes to get up to 350 degrees and struggled to get to 400. The pizza box wanted 425 which it did not make it even though the manual said 450. Seems like more heat blows out the vents on top than it should. Once it makes it to 400 as it cycles to maintain temperature it varies 25 to 50 degrees. Called GE support, they said preheat takes 20 minutes to get to 450 degrees. A service call is only covered under waranty if the technitian changes a defective part. They wont come by and check if its operating to specs.Anyway the convection part is not being used at my house and I wasted money for that option. Another thing that bugs me is the turntable on off feature.You can press the button and stop the turntable but it wont stay off. Every time you open door or change time you have to press it again.I would like to program it to stay one way until I tell it to go the other. To summarize, the convection part is useless and its to much money for just a micro.