Cellphone problems within 7 days but no excha

Last week Monday, 07 October 2019 I went to buy a phone(Mobicel R1) at Jet in Durban with address 441-453 West Street, Durban, Natal. The cashier that was helping me told me that if the phone had problems within 7 days, I can return it and they will exchange it with another phone. But if its after 7 days, they will make bookings for it to be repaired. I even signed the agreement on the proof of purchase that has terms and conditions. Ever since I started using the phone, it has been freezing and when I am using it the time stops(it does not move at all). Yesterday(14 October 2019) I went to the store and fortunately the cashier that was helping me to buy it was present. I told him that the phone is freezing and that the clock does not move when I am using the phone. He then asked me that what then do I want. I told him that since he said that the phone will be exchanged if it had a problem within 7 days, I would like it to be exchanged with another phone. With a bad attitude he asked me that why didn't I bring the phone over the past weekend. I told him that I am a student and I was very busy during the weekend as I was studying for my exam which I was writing yesterday(14 October 2019) and since I knew that a day is made up by 24 hours I thought that I am still within the 7 days period. With an attitude again, he asked me that where did I ever heard that it counts per 24-hours. I said to him that he never mentioned to me that according to Jet stores, a day is 12 hours. He just told me that it will be exchanged within 7 days. So I ended up not being helped.. I even told him that before I signed the terms and conditions, I read everything and I haven't came across with anything that says that a day is 12 hours for Jet. I even gave him and asked me to show me that and he only showed me what is written there that 7 days.

Because of this I feel that my consumer rights according to the Consumer Protection Act have been violated. Which are: -Right to Disclosure of Information -Right to Fair and Responsible Marketing -Right to Fair and Honest Dealing -Right to Fair, Just and Reasonable Terms and Conditions -Right to Fair Value, Good Quality and Safety

I would love to be helped to exchange this phone because once it freezes within 7 days of purchase and has problems with time, it means that it will forever do this.