bad service

I bought a huawei Y7 on the 5 July 2018 using my mom's account on Sunday 8 July 2018 the i noticed that the battery of the phone is not lasting and the touch screen of the phone is freezing i than took the phone back to the store on the 9th July 2018 ii went back to Attlyn mall foschini store were i bought the phone and told them what am experiencing about the phone. I was than assisted by a lady call Oliver she told me that they need to take the phone for assessment so that they can check whats the problem regarding the phone.i than asked them why don't they exchanged the phone for me cause the 7 days return policy is not yet up she was rude to me and told me that they cant exchange the phone for me i asked how so cause on the slip its states that if you have a problem within 7 days you have to return the device to the store . i than asked for them to refund me they refused . I called the head office and the lady told me she will call me back after talking to the store but they haven't