Telkom SA Misrepresentation

I entered into a cellphne contract with Telkom SA. It was a Hisense phone. Only to find that its not a Hisense but aHuawei Y3. The deviced arrived in a Hisence box and it was also branded Hisense, found out when i was hospotting my other phone that its a Huawei Y3 and not Hisense. My biggest problem is that the device has never been on for more than 15 minutes without switchinf off. I duspect its a reject from Huawei then they changed the brand to Hisense to lure customers. I have since informed them about the malfunctioning of the device and of their misrepresentation about the brand of the device and akso requedtingvthe contract to be cancellex fue to misrepresentation but have not yet gotan answer yet for about a week. I need to be advised on what next step should i take.