What is going on with the latest update?!

My phone has become useless after the latest update! I had to get ahold of customer service just to get the phone to work again and now it restarts on its own at least 5 times throughout the day and never finds service. So it drains the battery looking for service. Before the update I had great service. I know other people are experiencing issues as well. Is this another illegal issue from apple to have people buy another updated phone. If so, I’m going back to android. Any suggestions on how to fix the problems I’m experiencing?????