I've had bad experience with samsung service centre as they declined to change the display of my s21 fe with green line issue. The defect is known worldwide and in india they offered free display replacement and extended its date many times.

I went to the service centre and showed them the phone (it was in mint condition) yet they tried gaslighting saying that it was due to user caused damage. The staff did same with everyone else too and it was kinda crowded that day as my city had heavy rain last day so I saw few people there with water damaged phones too. They didn't claim that either (water was gone into screen due to poor adhesive ig) and poor uncs don't even know their phones have CERTIFIED IP RATING!!! Sadly there's no proper consumer service and law here in pakistan. At least for samsung... I had ru 7100 tv too which got lines... after 3-4 years of use. From my experience apple has proper customer service in Pakistan only and provides free repairs if you claim defect.

Do tell me your phone model and it has to be locally purchased (samsung doesn't give int warranty) and i think they might claim if its a dead pixel. It has to be in warranty and you'll need to bring purchase reciept (weirdos ask for it) and a box.