iphone x green line

Hello Everybody

I bought Iphone X 256 GB in Georgia, city Tbilisi, at iplus.ge store and after few days on display appeared Green line. When I took to their service center, first they told me that they need to restart system and then if still there will be any green line they should open up the iphone and detect the problem.

I told them that its defect of phone and want to change but they still keep saying the same. I dont really want to left my phone to their service center and even let them to open my phone. I have 30 day guarantee that says: If there will be any phone defect they will change. I think that they dont want to change and trying to extend my guarantee agreement.

I want to ask you to official Iphone based in USA is green line defect? and what you do in this case? should they open it up? or replace it immediately . Unfortunately we dont have official representatives in Georgia but still I need your help. as it cost to much money and they even dont care about their customers. 😟

What can you suggest me to do?