BIDVEST BANK MANDATE FORM NOT WORKING

I have signed the mandate form many times in the past with no problems. However, now when I sign it, it says completion error. They have put my first name as my last name, and there is no option to edit it. I have sent them countless emails, and nothing has been done about this issue. I am so frustrated that I cannot access my money, and that no one is willing to help me with this huge issue. Their customer service is shocking!!! I need to receive my money!!!!!!!