Take my phone back due to a mistake on MTN side and not sending it back or provinding any feedback :(

I initially did an upgrade through the MTN Direct call centre on the 8th of August for a Samsung S8+ and was advised that the phone would be delivered within 5-7 working days. The upgrade deal included a free tablet, which the call centre agent assured me would not come with the delivery but would have to be claimed via the Samsung Rewards application on the phone. I made arrangements with the courier company for delivery. I had to cancel a day of leave in order to be at the office to take delivery. Courier never pitched. The delivery was then re-scheduled and eventually received the phone. A few days later I was busy setting up my phone and the same call centre agent phoned me to say that they had made a mistake and the tablet actually was supposed to come with the delivery. I then requested her to send me the tablet seperately. Apparently this is not an option. I had to return my phone to the nearest MTN direct shop and the would then send me a new phone with a tablet. I even requested that they send the courier with the correct package and we simply do a swop. Also not an option. Really stupid process to be honest! I kept calm and returned the phone to Carnival Mall MTN Direct shop and was cc'd on a mail requesting the phone to be collected. This was on the 27th of August 2017. I have since called the call centre numerous times to request an update on the progress and I have had 2 calls being dropped in my ear, told me that the call centre agent that initially assisted me would phone me back with an update. I have been promised 3 times that she would phone me back. No call received as of yet. She is simply not interested in helping me or I am missing something.

I am really hoping someone can help me just get my phone, this is really hampering my business at the moment!