No IPhone 11 available for upgrade for the past 5 weeks

I am very disappointed with the service I received from Cell C. I have been a loyal customer of Cell C for the past 4 years and even moved all my business phones over to Cell C. Two of the contracts were due for upgrade and were upgraded to I-Phone 11 as advertised. It has been 5 weeks and I have not received the phones. I contact the store on a daily basis and every day I must hear that they have not relieved any stock from the Warehouse. Do you want me to cancel the upgrade and rather take my business to another service provider? Why are you still promoting the phone if you do not have any in stock? I am really at wits end.