R3000.0 debit order deducts weekly

I called the offices of MBD to arrange the debit order to be deduced every month end to my surprise the debit order was arranged to be deducted every week,due to the insufficient funds in my account it bounces and I get charged for that. I have tried several times through email and telephone call to have this problem sorted but no luck,my bank charges have piled up to a point that I am struggling to cover them and I told them about the charges they said I must send them my bank statement together with my ID copy for them to have those bank charges reversed till to date I haven't got nothing. I tried to have it stopped completely I am not winning. I really need urgent assistance,this is killing me as I am financially struggling already