Screen Glitch - Dell Inspiron 5558 signature edition

Hi,

I bought my Dell laptop in December 2015. After some software updates my touch wasn't functioning properly. (i.e Without even touching the screen it would select random options on the screen in the same place repeatedly). So I disabled my touch screen completely in late 2015.

Lately it has begun to show white and black lines on the screen and when I connect it to another desktop there isnt any issue. But I am unable to use my laptop normally without extended display.

I have tried the built-in test for the screen. Test was successful.  I see this issue with many laptops. How should I resolve this issue and why doesn't dell take care of these issues at the time of manufacturing and there by avoiding a frustrating experience for its users.