Refusing to exchange a 4 day old Phone

On Monday(27/04/15) I went to Edgars Highveld mall to purchase a new cellphone, I found a cellphone(AG Chrome Ultra) and purchased it with no hassles. By the next day(28/04/15) the phone started freezing and not responding to commands. So on the Wednesday(29/04/15) I took the phone back to Edgars to exchange it, the female then advised me to keep it another day as she could find no problems with the phone. I then took the phone back home as they refused to exchange it, but the phone was still doing exactly the same when I got home. I then returned on the Thursday(30/04/15) to exchange the phone as I kept it one more day as per their request, they then exchanged the phone after a slight dispute in the store. I took the new phone home and tested out the new phone and on Friday(01/05/15) the new phone started messing around again. So on Saturday I went back to inform them of the new problems that had arisen with the new phone, the lady then \Autosynced the data"to rectify the problem"