Share your experience!
Have you tried a software repair until now?If you repair and do not fix the issue,it means hardware is the problem.
Download sony update service:
http://www.sonymobile.com/gb/tools/update-service/
Install,open and follow the instruction given there to repair.
Take the phone into service.If you go for software repair,back up your most important data because it will erase phone memory.
Very strange,so now the phone works fine?
Well,good it works now.