FNB Business Zero inConnect Department and CellC poor service

I have been struggling to get my FNB Business Zero cell phone working for 2 months. I had 3 cases logged and to no joy AT ALL. My problem is I cannot receive SMS's and phone calls from any providers except FNB (CellC). The cases was escalated, swear word in South Africa, I had to call the inConnect number, 135, and hear what the status is. I received a call on Monday where the person told me that CellC says the problem is fixed, which I proved to them that it is not. I used other handsets and still the same, the handset I am currently using, Samsung A01, done a factory reset and still the same. I have done SIM swops, twice. I made the suggestion that I will rather get a new number and SIM card and try again. I have done this morning, the agent at the branch, Centurion Mall, linked the new SIM card to the wrong account. Can the people of FNB not do something correctly from the start? Now I have to go into the branch again and asked that they link the card to the correct account. Case number logged: Cas585310B9P6F1

Can somebody, PLEASE assist me with this problem?