New pep phone with a default

I recently bought a Hisense U964 at pep home at Seshego circle,to my surprise they sold me a phone that was on display I asked them if it’s not going to give me a problem and they salesperson assured me that it’s not, the phone was a terrible defect that heated up so bad when charging,switches off by itself and unfortunately I was travelling outside of the province and I couldn’t return it during that week of purchase but I returned it after a day or two of the time given to return it and I was told they will have to take it in for repairs,I told them I didn even use the phone because of how bad it was,ok it was booked for repairs which took more than 3 weeks,now the phone is back with the same defaults..Please help me with this problem I don’t want this s**** of a phone and I will never buy a phone from pep again