Upgrade phone not working

My fiancé upgraded his contract and got me a iPhone 7 as a gift from the Mtn in rustenburg because that's where his stays and I stay in Pretoria.so he had to buy a contract simcard selling for R112 for the phone,he bought it and came with the phone to Pretoria to give me I was so happy so he put the sim card inside for me and did some setting and buy using WiFi and when he was done the phone didn't have service so we switch the phone off for almost 8 hours but nothing happened it still said no service. When he left for rustenburg he took the card for the sim and after work went to Mtn that was on the 13th of this month olebogeng the person who helped him was not working that day and the person that help him said that olebogeng sold him the prepaid sim and the person didn't even border to solve the problem so my fiancé left the store and called me and I said he must live it when he comes back on Saturday he can go to Menlyn and on Saturday he went to Menlyn they made him buy a new sim and said after inserting the sim he must switch off the phone for 3 hours and he did that but still nothing. I got over the phone and ask him to live with the phone when he is going back on Monday morning and return it to Mtn I Dont want it anymore,it was a nice gift but it was useless to have it because it wasn't working. On Monday the 18th he went back to the store and it had a note that it was closed on the 15th and he went to another Mtn store close the closed one but they said they can't help him.he wasn't going to return the phone like ask him cos unlike me he is patient and just wanted the phone to work but after that service he called me angry saying he is going to tweet about this and i told him he shouldnt have left the store without being help what do they expect him to do with a phone that's not working and yet they will want payment for it.I was over this but now I am angry because they made him angry that man is always calm nothing gets to him easily but the service of Mtn got to him.and he even says he will reverse his payments until they call him maybe then they will help,I just want that phone to go back it has trained us emotionally.