FNB EMPTY MY 3 year old Credit Card for only FICA

I went to store to purchase products and my credit card decline twice, which I knew is impossible! I check my internet banking app and my credit card balance suddenly where R0. I though I was hacked and all my money has been ******. A few minutes after I received a message from FNB stating I need to upload FICA documents. How?????! I have this card and used it for Almost 3 years now and NOW you want FICA docs and take away my Credit Card Balance???? This is madness. How is this possible that FNB can just do this?? I get no response from the banking TEAM and I need Answers! I didn’t even received a mail where to upload these documents... come on FNB, I think this is a bit unprofessional??