More than a month and no courier from Vodacom

I requested an upgrade to an iPhone 6S in early October. On 29 October, a phone was eventually delivered, but it was an iPhone 6, not a 6S. I did not open the package, and immediately reported the error. I was told a courier would collect the incorrect phone and the correct one duly dispatched. This has not happened, despite numerous calls. Every time I speak to a consultant, I am told that she can see that the issue has been \escalated"(?) and that she will phone me back. That promise has probably been made ten times at least and I have not been phoned back once. This despite the fact that Casey crossed her heart and hoped to die if she didn't phone me back in an hour a few days ago. I have spoken to her since and she is still alive and well and at the call centre and has STILL not called me back. I have offered to bring the phone in myself"