Google Nexus 5 - Constant rebooting - replaced power button. Found only 2 places in London that offered this service for my phone. LoveFone was central (easier to reach) and cheaper by a long way. I booked an appointment in the morning, walked in during my lunch break, had a coffee in the nearby Caffe Nero while I waited (only 45 mins) and came back to a fully functional phone. (Power button replaced for £39). They gave me time to check I was happy, and they offer a year warranty. Only been a day.. but they offer a year warranty.. so I'm confident if anything goes wrong I'll be right back there.