Inconvenience Sim card stopped working CellC can't do anything about it

So my sim card that I have been using for years randomly stopped working or getting network. I called the customer service and was told to go to the nearest branch which I did in Vangate mall. They said I need to get an unricard sim and come back. Today I went back and were like unfortunately I cannot be assisted. The inconvenience this will cause in my life this is the number I used for my job applications, bank notifications only to be told there's nothing that can be done.