New broken phone not replaced after more than a month

Upgraded on black Friday at MTN Bethlehem, they sent me the phone via courier. Upon receival the phone did not come on. Returned the and they said it is not working and will have to be sent in, this was on the 3rd of December, told it would take around two weeks to receive a new phone. Every time I have to enquire about the status of my phone. After being told it has been sent in and having to enquire again, I was told on the 5th of Jan it was sent from one repair centre to Midrand. Today is the 11th of Jan and I still have nothing. The manager is not answering his phone, the sales people are not of any help, I want to sort this out myself now, I have asked for phone and reference numbers to sort this out. The branch is not answering their phones as well now. This is not acceptable!!