EXTREME SERVICE DISSATISFACTION AND THEFT FROM MTN

I upgraded a contract on in June this year to an iphone 12 but last month the phones screen froze. I had trouble booking it in for repairs as it is still under warranty and it was a telesales upgrade. I now am looking for my phone and I have spoken to the courier company DSV who was sent by MTN to collect the phone from me and more than 16 different consultants from MTN but NOONE can locate my phone. I am paying so much money for a phone noone can account for!!!!!!!!