My camera freezes and I can't take pictures

I got the iPhone 7 from att Sunday and yesterday my camera stopped working. I take a lot of pictures and chose the 7 because it had a better camera than the 6 and 6s. The iPhone 7 I bought is a black 128 gig. Sometimes the camera works but 90% of the time it doesn't. The front facing camera almost always works it's just the back one. I plan on bringing it back as soon as I have time and exchanging it for a new one unless someone has a fix that will last a week at a time instead of a restart which last 5 minutes. I've updated it, reset it, restored it, restarted it. I'm going to set it up as a new phone tonight. Thanks in advance for any tips on how to fix it.