Online banking broken

It's a shame that it has to go this far every single time before I get helped! I reduced my overdraft via online banking and suddenly my account is so far in the red I won't be able to get anything else paid. I took my current balance and deducted the amount I wanted to reduce my overdraft with. Online banking decided it has to reduced by A LOT more! Like last time I phoned FNB immediately to reverse it and, like last time, they told me there's nothing they can do. Now, like last time, I need to Hellopeter you first before, like last time, you can fix it. Please phone me urgently, I need to get this reversed! I have already sent you two e-mails as well with NO RESPONSE!!!