Courier who for why???????

I upgraded my contract with Cell C on the 2nd of December. Delivery usually takes 2-7 working days or something like that. It is now the 25th of December and my device has still not been delivered. When I call into Cell C to complain I'm told I just need to wait and their is nothing they can do, this is totally unexceptable. The courier company used is Courier It. Nobody can get hold of them because their contact lines don't work. I did get hold of someone and she told me they dont deliver anymore. I have been a loyal customer to cell c and they have been a good network provider thus far. I do not want to take my business away from Cell C because of another company that cannot fulfill their service obligations. I would appreciate immediate assistance in this matter.