Green horizontal line across new laptop screen

So this is a brand new HP laptop (bought 6 days ago) and there's a dotted line across the screen that I can't get rid of.

I'll happily return it but the Curry's PC World store that I bought it from is difficult to to get to. Can I go to a different store? 

Or, preferably, is there a way to fix my laptop?

Thank you in advance.