Share your experience!
I've had numerous problems with my Xperia XA, it's only 3 months old.
I have huge issues with the phone being able to perform most functions.
It's also been sent off to repair as it's under warranty. They didn't do anything except change the battery.
First day I had it returned from the repair centre, the whole phone crashed and restarted twice.
It is by far the most temperamental and inefficient phone I've ever owned.
What on earth can I do?
When you had your phone in the service center did they reinstall the os? The only thing you could is "repair" with Xperia Companion http://support.sonymobile.com/global-en/xperia-companion/
Be aware that you will lose all data, so better backup everything.