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Hi @Cristian1112, welcome to our community!
I'm sorry to hear about your phone. 
If you look at the top of your phone you will see a small Sony logo, to the left of it there is a small sensor located, this is the proximity sensor on your phone.
Make sure that this sensor is not covered by a protective case, film or glass like @uliwooly recommended, also make sure that there is no dust or dirt on the sensor. You can use a clean and dry cloth to and wipe a bit on top of the sensor.
If the sensor is covered by something it will not work correctly and the screen will for example not light up again until the one you are talking to ends the call.
How did the sensor work when you did the test that @uliwooly recommended? Does the phone vibrate directly when you start the test or is the sensor working correctly in the test and the phone only vibrates when the sensor is covered?
If you don't have any case, film or glass covering the sensor and you have wiped it clean and you are still experiencing this behaviour I would recommend that you reboot your phone in safe mode and either make a call while in safe mode or that you do the diagnostics test again.
Let us know how it goes! 
Hello again!
Was there any difference when the phone was rebooted in safe mode and you ran the diagnostics test? If it's working in safe mode a third party application is the cause.
I would recommend that you start with uninstalling the latest apps that you installed in your phone prior to the proximity sensor stopped working.
If you experience the same behaviour while the phone in rebooted in safe mode the next step is to perform a software repair using Xperia Companion. Do note that this will delete all data stored on the internal storage in the phone, so I'd recommend creating a backup using Xperia Companion before performing the repair.
Keep us updated!
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