customer service

I am not happy about the service I'm getting from ackermans, I bought a cellphone on the 25th of May for my wife and that cellphone only worked for 2 days after that it died, I took the cellphone back and they said they taking it for repairs. The phone went back for the whole month and when it came back it worked for a few days and it died again, I took it back and they took it back for repairs and it took the whole month for it to come back with the same fault. I took it back now and the manager said I must come back after a month. I am not happy, I bought a cellphone in order for my wife to be able to use the phone. Now I have to pay for something that doesn't even work. Why does the cellphone have to be sent for repairs every time. Is it not a new phone? It's either I get a new phone or they take back the phone and credit my account.