I bank with them every month beginning July 2022 I get debited R500 it's now R2000 that I have lost

I bank with them every month beginning July 2022 I get debited R500 it's now R2000 that I have lost. I sent a claim via email and social media and now the have abandoned my claim because I refused to answer their security questions, reason being 1. I'm not applying for a product where they have to make sure I'm not impersonating someone 2. I'm loosing money and asked them to investigate. 3. They have all the tools to investigate who is committing ***** on my account or whether it is mere negligent. Am I being unreasonable? So they refuse to help me and ignoring my emails