Failure to honour 7 day exchange policy

So on 23 December 2015, we made a purchase of a Nokia 220 cell phone (black) at Pep Stores, branch 6137, Waterfall Mall Rustenburg. The cell phone was purchased as a Christmas gift for my grandmother. On the 25th when presented with the cell phone, the phone was non responsive and the keypad kept on flashing. So on the 28th of December the phone was returned to the branch for an exchange since it was within the 7 day exchange period.<br> <br> The Manager (Portia) informed that there's no way the phone could be exchanged for another as 'Mtn does not provide a guarantee on their cell phones' and also the fact that if one buys an Mtn cell phone, that person does so 'entirely at own risk'. And if Pep was going to have to repair the cell phone then we would have to be charged R300 for the repair.<br> <br> Pep claims that 'Faulty handsets may be exchanged provided it (1) is within 7 days from selling date, (2) it has not been physically damaged, (3) is returned with original packaging, accessories and proof of purchase. All of the above conditions have been met so an exchange should not be deemed as challenge unless Pep staff do not understand the terms. Pls assist with the matter before escalation.