Capitec - UNAUTHORIZED SET OFF

An unauthorised set off was app**** to my account I am totally disappointed with the service i received from Capitec. I received a message today saying that one of my accounts was in a negative balance and they have app**** a set off- meaning they have transferred money from my account with a positive balance to the one with a negative balance without my permission or even letting me know that this is it. Their terms and conditions do not even have a clause regarding "set off" . This is not something that was ever communicated with me. It I also something that I have never agreed to. I was not even aware that my account was in negative as on the app, it just showed a balance of R 0. 00.