Hi, welcome to iMore.
Sorry to hear you're not enjoying your iPhone 5.
When did you buy it? Where did you buy it from? Was it a new device or a second hand device?
If second hand device, how long has the person you bought it from been using it?
Feel free to make an appointment with the AppleStore via
http://support.apple.com to have your iPhone diagnosed and tested. Apple has an amazing customer service and I'm confident you'll leave the store satisfied.
Please join our forum to answer in this thread so we can be of further assistance.