Unauthorised billing leads to bank charges

I am beyond furious with A &G. I called and took out insurance for a vehicle I was about to purchase. I did not go ahead with the purchase and cancelled the policy before the initiation fee and pro-rata fee was to be deducted. I emailed my cancellation to A&G. On the Friday I emptied my bank account leaving a balance of R 0.00. On Sunday there was a deduction from A&G. The amounts were returned as there was no funds in my account, however, I have now incurred returned debit order fees for a debit order which was to be cancelled by A & G. I have incurred R 230.00 in bank charges for this debit. This amount is to be refunded into my nominated account or I will have to proceed to the OSTI.