Unauthorised debit order

Capitec has allowed an unauthorised debit order to got through my account. I did a debit check for a specific amount and that amount was debited on the 25th as authorised. Now what I don't understand why capitec would allow another unauthorised debit go through on my account for a n amount I did not authorise. I can't reverse this unauthorised debit order on the app. If my money isn't returned I will be reporting this to the OBS. I don't understand why I can't reverse an debit order I did not authorise. My debi check was for.a specific amount on a specific day. Why would the bank allow for a third party to be able to debit an account again for an amount that was not authorised on a day I did not authorise. I want my money back or I'm taking it to the OBS