Debited order not done-incorrect bank details

It appears my banking details are incorrect but the cell c consultant insists that it is. I've received an sms telling me to pay my account or my name will get a bad record. When I took out this contract i asked that my account be debited on the 15th of each month. The money was apparently put back into my account because I had no funds. This is incorrect because even if the money was put back my bank statement would stipulate this. Please follow up with the person who did my contract. Ive given him all the correct info but he seemed to have captured incorrectly into the system. I cannot be inconvenienced to pay the money into ur account at nedbank because next month I'll be going through the same thing. Please do something and take the money I am owing u guys due to the clumsiness of the person who captured my info wen I took out this contract.