Bad Service/No existant service from Cell C

The service that I have received from cell c after being a client of theirs for many many years is absolutely terrible. I upgraded my one phone contract through their upgrade department, to an Iphone 12 Pro Max 128g Graffite in colour, which the consultant confirmed they had in stock on the 16th February 2021. I was informed that I would receive the unit within 5 to 7 working days. Today it is exactly one month later and I have still not received the phone. When phoning their customer services department I get told that there is no stock, however when I upgraded they had in stock. I have spoken to the Manager of the upgrade department who also promises to phone me back and that phone call never happens. I would like written feedback as to why a loyal client to the product gets such bad service.