Empty promises re upgrade cell phone delivery

I upgraded via MTN Direct on 25 Nov and was assured my new cellphone would be delivered by 27 Nov. During the past two weeks I have called both MTN Direct and RTT logistics (responsible for the delivery) a number of times per day but am still without a phone. RTT scheduled 4 different delivery dates/times this week alone without delivering the phone at any of the arranged times. Any attempts to get hold of a supervisor at MTN Direct failed. Each call centre agent tells me a different story, drops the call or passes it to other call centre agents who cannot assist, etc. The original call centre agent phoned me this morning to once again assure me that the phone would be delivered today, in spite of me requesting that this upgrade be cancelled rather, and still no delivery. Any attempts today to get hold of the RTT consultants at the Cape Town branch responsible for the MTN contract failed. I would like to cancel this upgrade with immediate effect since MTN is unable to fulfill their part of the contract by providing me with a new cellphone.