hi sense 55 inch led tv

Hi I've(rachael naidoo) bought my tv 4/2/2016 from joshua doore.Problem is that I only can see half picture.I've taken the tv to the store 5/04/2016 was told they will call me within 2 days.No feedback has been received.if I understand correctly the item is still under warranty and guarantee...so I shud have been given a brand new one.This is nonsense I've paid alot of money for this tv and I want answers.