Same problem here. Mine started to get harder (power button that is) to use, then became nearly impossible. Now, when I'm in the middle of doing something or using an app, the off screen randomly appears as if someone was holding the lock button down to activate the "turn off" feature.
I of course like most depended on my I-phone 5 to make it the 2 years if not longer, so I chose not to buy the 99.00 extended plan.
I love my I-phone, but I have found that like many companies, Apple just nickles and dimes everyone for every little thing. Like a 19.00 dollar support call.
Call me stupid, but doing something about issues like this with a company as large as Apple should just be 2nd nature. Offering support thats precise and on time for hardware related issues should just happen without question. It helps the entire culture of a company, and puts questionable consumers concerns to rest.
I really can't afford to have my phone fixed, so i suppose I will have to abandon the 5 until I'm able to upgrade, and go back to my old android phone :-( I barely got a year of use. This is so depressing.
I don't even have an apple store within 200 miles just small retailers.