Double Debit. Not agreed to.

I spoke to Elvis Senne on 23 Jan 2015 regarding a debit order that MFC loaded incorrectly on my profile. As a result one installment was missed. <br> We agreed to have the one missed installment spread over the remaining financing period. However, this was never done as I received notification this morning that my vehicle installment went off double. I need one installment refunded to me immediately as this was not the agreement, and cannot afford the double debit. Neither was the incorrect loading of the debit order details as a customer, my fault.