unresponsive section of touch screen

[Mattia]

My xperia z is less than a month old but the middle section of the display is unresponsive to touch.

I thought it was an hardware problem, but I tried to remove and reinsert the SIM card and it started working again. Then, less than 24 hours later, the touchscreen became unresponsive again. 

This time removing the SIM had no effect. I tried with a complete reset and everything, but nothing changed.

Have you got any suggestion?

[Uliwooly]

Do you have an extra protective film and/or case?

[Mattia]

I have a protective film, but I don't think it may be the problem because:
- The unresponsive section is very precisely defined, a line talk a couple of centimeters wich run from side to side on the screen
-After I removed and reinserted the sim card it worked just fine for a few hours
-It is not less responsive to the touch, it is completely unresponsive

[Uliwooly]

Test your screen with

https://play.google.com/store/apps/details?id=com.sonymobile.androidapp.functiontester

[Mattia]

Thank you, I have tried that and apparently everything works well but the touch-screen.
I think I will bring it to assistance, but considering it is a 2hour trip from here I wanted to try and find a solution by myself before

[Uliwooly]

if its a hardware issue there isnt much you can do, keep in mind that if you open the phone it will void the warranty