MTN IPHONE 13 contract

I bought an iPhone 13 at MTN South Africa last year November. The phone switched off after 2 weeks . I took it back to an MTN store , they told me that they’ll fix it. The phone came back after 21 days and guess what? It stopped working again. I had to return it , they told me once again that they’ll fix the phone. That was back in January , went to fetch the phone in February and they told me it’s not fixed. Mind you they’re still deducting money for a phone that is not working. We’re in March and my phone is still off. MTN is the worst store in the whole of Sourh Africa. I need a new phone ASAP! MTN SOUTH AFRICA do some please. I’ve been patient, I can’t take it anymore. You don’t even deserve that 1 star.