Online ***** poorly handled!!

My phone was ****** and whoever stole it managed to unlock it. So I had a Standard Bank App on that phone which they managed to amend it and bought prepaid worth about R3000.00, I called the ***** line and a case was opened after a week or so they called me to let me know that since it was just prepaid my claim has been declined because the bank can not reverse that. My issue is if that is how they handle such cases then what? the online App must have high security and if anyone can simply make changes to it and take your money then no ones money is safe with Standard Bank. I am pretty sure they have insurance to cover such cases so if they are failing to help me where does that leave me? I am really not happy about this issue at all, there must be a better way to handle such situations. This is totally unacceptable. How can someone make changes to your account and Standard bank tells you there's nothing they can do? All they can do is deactivate your account immediately after your money is gone, It is totally not safe!! I demand something to be done about such issues, otherwise Standard Bank can't be trusted at all with your money. I am so mad!