Bad service cell c

I did an upgrade on the 12th of August 2015 via the call centre and specifically requested that the phone gets delivered at 16:45 and the courier company that is from Ram delivered the phone on Monday 17th of August at 12 the afternoon. I logged a call the Tuesday for the delivery at my work and received the phone on the 19th august 2015. Today the 26th of August 2015 I was busy on the phone and the phone froze and the battery started to get warm. I did not do anything but to reboot the phone and the phone after that did not even want to switch on. I immediately took the phone after work to cell c walk-in store at canal walk. Where I logged my complaint with what is wrong with the phone and the lady said to me that they could not exchange the phone and that the 7 day period has elapsed. According to the contract I am in my 7th day from receiving the phone and not the 8th day as the lady said at the store. They referred me to a direct store tygervalley which is closed at 7clock. The lady said that the phone needs to be booked in for repairs, I disagree because i haven't even started making payment on the contract but I must be in a possession of a repaired phone. Very disappointed!