Lines on screen after repair

Hi, I dropped my phone a few weeks ago and finally saved up the money to get the screen replaced. I was so happy today when I got my phone back but within 3 hours there are two lines on my screen- one horizontal which is black with a white line on top and one vertical which was a thin green line but now is getting thicker and has turned white. The screen itself is working behind the lines and the touch is still working. When I took it back to the shop they were not interested and said that I must have dropped it ( I have not dropped and have been so gentle with it after finally getting it fixed) . I'm not looking to say he did or didn't do this but I'm unsure if the screen is broken again or it could just be a loose wire or something I can fix myself.

Any advice would b great as I love this phone and really want to get it working again :)

Thanks :)