Blackness Creeping Up From The Bottom Of Display

Last year I had to get my display replaced because it completely stopped working. It was under warrenty.

A few months ago a green line appeared at the bottom of te display. After contacting support they told me to reset the NVRAM wich I did. I would come back occasionaly but for the most part it was ok.

Recently it cam back and has been slowly moving up. I can barely see the icons if the doc is at the bottom!

Is this a hardware or software issue?

When I talked with support the first time they said if the NVRAM thing didnt work there would be some setting that could be changed that might fix the issue but I wasn't able to get any more info.