I have a Verizon iPhone 5. Other than being on its third battery, it has worked well for the years that I have owned it -- until now. Soon after 9.2.1 came out with the announcement that it plugged a security leak, I backed my phone up to my computer, then upgraded to 9.2.1 (using iTunes) from whatever the most recent iOS 8 was. The phone immediately became unstable. It crashes several times a day. It can be just sitting there, or I can be doing anything with it when it crashes. Something as simple as waking it or clicking on an icon can take seconds or minutes. The lock button has become intermittently unresponsive. (It worked fine under iOS 8.) Sometimes when I click on an app icon to open the app, the icon expands to fill the screen for several seconds until the app opens. (Zoom is turned off -- I double checked.) Once, the phone's screen went black and the phone was unresponsive to the physical buttons. I knew that the phone was on because I could place calls using the car's Bluetooth. It took several tries doing a reset (power + front buttons) to get it to work again. Upgrading to 9.3.1 has made the phone marginally more stable. Now it crashes only a couple times per day. With iOS 8 and earlier, the phone may have rebooted on its own maybe two or three times in total. I do *not* have the booking.com app, nor have I ever been to that website. Any thoughts about how to make the phone reliable again? I can't downgrade to iOS 8, alas. I wish I could.