Mtn
Upgrade ordered and followed up and still no deliv

I was contacted in April to do an upgrade on my contract which I accepted.
They told me delivery would be asap as they have stock of the S4 on hand.
I call every day querying when my phone will be delivered and am told I will get it when the couriers contacts me.
And they also informed me that they will get my sales person to follow up.
After several phone calls and being transferred around I eventually was told the couriers tried to call me for delivery on 2 May and 4 May (a Saturday?) for delivery and I didn't answer my phone so it has been sent back.
My records can be pulled - I don't have any missed call or voicemails from the supposed couriers.

I do not understand how this can happen and a sales consultant does not follow up on their cases?
I also am very dissatisfied that I am paying the more expensive contract price for a phone I may never receive.

And when I speak to MTN Direct everything is made out to be my fault..

I just want an honest answer as to where this phone is and when I can expect delivery or if I can come fetch it otherwise I will be terminating my contract with immediate effect as non-delivery of goods does not constitute a sales agreement.