Cell C contract not delivered and not feedback or assistance received

I ordered a phone from Cell c on 14 December 2024 with a sales consultant via the phone and I was advised the phone will be delivered the following week through the courierit company. I still have not received the phone and Cell C supervisor/manager has not returned my call and there has been no effort or feedback from Cell c and when I call to ask them to follow up they advise they can't? How is it even possible to do business with someone but you can't follow up if your orders are not delivered? Or did the person not want to assist? I need the phone delivered by 31 December 2024 or I'm cancelling my contract. Its very unprofessional of them not to even try to assist in this matter.