Cell phone not delivered

I cancelled my upgrade with MTN for an iPhone 5c so I could get the iPhone 5s instead. I got a call from one of their agents to help with the change to the 5s. This was about 4 weeks ago. I was told that the delivery would happen within 2 weeks. First attempt to deliver, they didn't call to notify me that they were at work to deliver the handset. I was 20 minutes away and I was told they could not wait. I get another call to attange for the phone to be delivered on 9 November. I waited the whole of that week. No delivery. I call them today (16.11.2015). They tell me that the phone was sent back to the warehouse on 13.11.2015. The person I spoke just did not give a damn. I asked her twice when the phone could be delivered. She told me two weeks. I'm seething because even the @MTNza twitter account asked me two times if I was assisted after they told me that my problem was escalated. I'm losing my patience with this company as if they haven't been giving problems already. God forbid that they bill me for a handset that I have not received because I've received the TopUp100 package twice already. MTN YOU ARE TESTING ME AND I STILL HAVE TO DEAL WITH BAD CUSTOMER SERVICE