Hi Boost cellphone

I bought a cell phone by the brand name of Hi Boost at Sportscene at their Golden Acre branch in Cape Town during the month of February. After two weeks in use the phone just stopped working. I took it back to the Sportscene branch and they sent it away for repairs in JHB.I had to wait for more than 6 weeks for them to repair the phone. The phone was working then on the 4th of May it stopped working again. I demanded a full refund but was told by the Sportscene staff that the phone must go back to JHB for yet another repairs. This means I have to wait for another 6 weeks for a phone which clearly doesn't deliver the service it should. I need advice on how to go about to get a refund or a replacement phone which cost the same but not a Hi Boost brand.