Share your experience!
The power/lock button on my xperia u is very hard to press and i doubt if i keep using it regularly, it might just stop working. Can i change screen unlock option from this button to something else???
search in play store.
If you are in warranty so why you are searching anothers option , just replace your phone..
Thanks for posting and welcome to the forum! 
If there might be something wrong with the key on your phone it sounds like it would be a good idea to let one of our authorized service shops have a look at it and fix it.
To get knowledge of the easiest way to proceed and handing your phone in please contact your local Sony Mobile support. You can find contact info on the link below.
http://www.sonymobile.com/gb/support/contact-us/
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