Unauthorised debit order

I opened an account with Ackermans and my instalment was for R258 and on 28 Nov 2017 I paid R400 at the stores. A debit order of the remaining amount was deducted from my bank account of R6572.57 on the 30th Nov 2017. My insurances, car debit etc are bouncing cause you had to debit my account. It is such an inconvenience even to my credit score if my other commitments are not met. How the hell do you go deducting so much from my bank account??? What am I suppose to do about my other debts if you cleaned up my bank like that?