Xperia SP - Internet and crashes & problems all round

[LGranger]

Will not connect to a computer no matter what I try (different computers/cables); crashes all the time whilst using apps, texting or answering a call; freezes and turns itself off when trying to unlock it - anyone else experiencing this or has and has fixed the issues?? Any advice is gratefully recieved

[Samuel1]

I suggest that you try to repair the phone software using PC Companion. The phone should be turned off during this procedure so it might work even if the computer doesn't recognize the phone right now.

Before repairing your device you may want to backup your information first. Check out this topic for more information on how to.
How to backup?

If the issue should still remain I think that this needs to be examined and fixed at a repair center. For more information about how to submit your phone for repair and where, contact your local support team.