FNB Smart Device refuses to give a new Phone

I bought my cellphone from FNB Smart Devices 2 less than 10 days ago and it just went blank and stopped working. I contacted them and was told by an agent to take my cellphone to SSS cellular where it would get repaired as it had a 2 year warranty. Even though my phone was couriered to me, i called them on exactly the 7th day, i was told that it was told the days are counted from the day i received it, even though the has OBF, I can confidently state that I have never dropped the phone and the screen has no cracks yet I am extremely disappointed with fnb considering that I have been a loyal customer. I am very angry as I had to constantly call and ask for updates. They are still debiting for a cellphone which I don't even USE and I am told I would need to pay the full value of the phone should I cancel and oh everytime I call the center it just messes up with my airtime. I am beyond disappointed shame!!!!