No help from customer care or in store

My cell c sim Card just lost its network. I attempted doing a sim swop telephonically to which I was advised that I did not pass the security verification. I was told that I had to visit a store who would then be able to assist me. Upon getting to the store they advised me that they could not assist because the sim card had been.pre-rica'd. I was once again advised to contact customer service who in turn told me that the number had been blocked for sim swop even though I still have the faulty sim card in my possession. Why is it so hard to perform a sim swop? I had all relevant details to which I could have been assisted. I am seriously thinking of changing my network