Upgrade of cellphone contract but no phone was delivered

I upgraded my cellphone contract with MTN Online on 9th March. My new device was not delivered to me, and I queried this via their call center on 24th March, which took me an entire afternoon of being transferred from one department to another, explaining the problem. I eventually ended up with the Retention Centre, who told me that the order to deliver a phone was cancelled, because the colour of the phone was out of stock. They then reactivated the order, gave me a reference number and told me it would be delivered within a few days. I have still, nearly two months later, not received my new device. Once again, I have spent the whole morning on the phone with MTN Call center, being transferred from one department to another, with no one actually being able to take responsibility for the query. I have even spoken to the DSV couriers, who maintain that they have not received the instruction from MTN to deliver the phone. Not one consultant is even interested in taking the reference number I was given on the 24th March which was supposed to escalate the query to a supervisor. According to the last consultant I spoke to about an hour ago, she has mailed the request to DSV to follow up. but I don't have much hope as to anything being resolved. The bottom line is I have been paying for a new phone for two months now, and I still haven't received it! Am I entitled to cancel my contract with MTN for lack of delivery of service? What is the alternative?