Samsung S6 edge , dead pixels

I recently upgraded my cell phone contract ( 10 july 2015) when I got home I discovered the phone had dead pixels, I packed it away and took it back the next day , which is today (11 july 2015). When I arrived at the mtn branch in kollonade a samsung rep told me that they must replace my phone, however mtn refused, saying I might have dropped it, however the day before I was informed that if I have any problems within 7 days they will replace it. The MTN manager then told me to walk to a samsung technician at dions to assess it, he then told me its dead pixels and could see the phone did not fall and that mtn has to replace the phone. I then walked back and had to wait for over 30minutes to be helped again, only for them to say they will not swop my phone and wanted to book it in... I refused. I'm now sitting with a phone that irritates me and as a mtn subscriber for around 20 years I am livid and when my contract is due for an upgrade again I will evalute my options and switch... #beyond upset and dissapointed