Angry customer

I have a problem with MTN , I have upgraded my contact with them ... I requested for an iPhone 7plus and I was given a I phone 7. I called the call center to assist me to change it. I took it to the nearest MTN Store (Hillcrest) I was told that I will receive an SMS with a tracking number that was on Friday 22/11/2019 till today I have not received it. The guy who was assisting me came back on the 03rd of December asking for my details... till this day I have not been assisted... I call the store no one is picking up the call I now want to cancel the upgrade I’m told I need to pay R9000 .... I’m very disappointed with your service. How am I supposed to pay for the phone I don’t have