If the iPhone 5 was purchased yesterday, you should still be within your free ninety (90) days of complimentary phone support. Was it purchased as a new device, or second-hand?
You have free options, such as the troubleshooting articles on this website:
http://support.apple.com/kb/TS3018
http://support.apple.com/kb/ht3647
http://support.apple.com/kb/ht1664
http://support.apple.com/kb/TS4562
Another free option is to get fifteen minutes of free troubleshooting support at a local Apple store.
Another free option is the one that you just used, asking a question on this forum.
Apple customers that pay for the Apple Care Protection Plan ($69 for an iPhone 5, to get double the length of hardware warranty, and twenty-one (21) extra months of troubleshooting support over the phone, live with an tech), get priority over customers that have chosen not to use that service.
Use the right solution for your needs. Some people are willing to pay for live tech support, others prefer the free options.