A brand new broken phone

My wife bought a phone at Ackermans in Westgate Roodepoort. She had the phone for less than a month and than the phone stop working. How can a brand new phone that came out of the box stop working in less than a month. She took the phone back and was told that they have a 7 day return back policy. My wife explained to her that she has own catering business and that she needs a phone. She was prepared to give extra money to buy another phone at the same Ackermans, but was again told about 7 day return back policy. She is frustrated because her business is standing still and will be standing still for the next 21 working days. She also says she does not want that phone again because she feels if it can stop working so quick, it will stop again. Again how can a brand new phone break within a few days???????? Attached is the slip that my wife got from the branch in Westgate branch.