NEW phone switched off after an hour and TELKOM wants me to await while they send in a repair and refuse to cancel as per CPA

I upgraded my sister's contract cause she needed a new phone asap. We get the phone at 6pm by 8pm when we get home the phone switches off. No warning nothing and does not want to switch back on. I try to put it on charge and not even a light comes on. I call Telkom 9am and tell them, I even have a video. I explain I want a new phone asap she says come in they will assist. I get there and the manager wants to book on OBF for phone to be sent for checks or repairs while I'm now without a phone. I ask for a new phone or to cancel its well within 24hours and I have video proof. The manager switches the phone on, it comes on, 31% battery life but he is insisting I just never charged it. He was rude and arrogant and of no help. Just cause it switched on doesn't mean it's not faulty. I don't want a phone that will not work every now and then and not be reliable. Kuben at Westwood mall is the face of terrible service. I see now all the bad reviews on Google and majority mention the managers Kubens incompetence. As per CPA I want to cancel my contract due to not only the faulty device but more so due to the terrible service of Telkom and more so the manager who was the worse customer service individual I've encountered. Kuben who the entire time sat in the back telling the sales person what to do, when I asked why didn't he come out and assist initially said he's too busy he is a regional manager with work to do which in turn made me upset. Absolutely ********** service.