Iphone performs tasks and makes calls on its own

My iPhone is performing tasks on its own. Usually I am holding it but I'm not performing any actions. Often it calls the last person dialed. Today, my music app had merged with my phone and created a new Home Screen folder called music (I keep my phone app by itself on the bottom of the screen along with Messages, Notes, and Safari). There are other instances of bizarre behavior, of it operating tasks on its own, and it's been going on since I received the phone. I have checked for unintended taps on the phone app, and couldn't find any. My battery does not drain quickly, so a spy app isn't running in the background. I reviewed all Settings, Privacy and Security as instructed by another apple post, and nothing is odd or unusual. I've turned off all motion and actions. Another post I saw (now closed) had a response and it said the iPhone is designed not to do anything without the owners permission. I'm sorry to say, this is wrong. It does all kinds of weird stuff, takes pictures, shuts off my watch sync... I'm not expecting an answer because no one wants to admit this can happen. Anyone else having this kind of issue? (I know I have seen other posts like this.) Thank you.