Cell c sim swap

Cell C is failing me dismally I have been using their sim card for over 20 years but now they can't help me with a sim swap. Just because I forgot one number that they need to make sim swap. I am running a business and all my customers knows that number and now they can't get hold of me. Even right now I am still using another cell c number because I love this network.i went to cell c store to make sim swap and they said they can't help me and even on the phone. Please help me I still need that number.