Phone is frozen after a week of purchase

I am really tired of Pep Stores Centro Rossettenville. Firstly the staff there are not friendly- I dont even want to purchase there anymore, I rather go somewhere else. Over a month ago my mother bought my daughter a phone at the store. After the first week the phone just got frozen. My daughter switched on and off and it continues to give this problem. My daughter took the phone with the slip to the store and the phone worked for a while, phone has been frozen for over 2 weeks now. It seems they do not want to help my daughter. Its easier for her to go to the store because I work out or sometimes get home too late.The service we receiving from this store is pathetic. My daughter needs a phone now it seems my mother just wasted her money buying a phone from this Pep Stores. There is no control in the store, even when we standing in line- no control and the cashiers show no interest- they never look happy. Its really annoying and pathetic that we pay for something and not to be helped. Please can we be helped- we do not have the money to just go and buy a phone. The phone is frozen meaning there is something wrong- it should be exchanged or something.