iPhone 6s restarts - apple offers a "new one" (refurbished) as exchange solution
Apple refurbished phones work great.
I actually use one right now, since the battery on my old phone had expanded. These phones have been tested well to make sure there's nothing wrong with them. Sure, you might get a recycled camera, but you'll never know. My phone was good as new when I got it, and I am still happy with it to this day.
The three-month warranty will cover any problems that a refurbished phone may have - bad battery, touchscreen, etc will be covered in that.
If you'd like to keep all your data, you can simply do an iTunes backup (not necessarily to your own computer as it is freezing), then restore that backup to your new phone.
Also, your phone is respringing (not rebooting)