Debit Orders

I'm a first time car buyer and MFC agreed to finance me. The first debit order was supposed to go off on the 28th of Jan but I hadn't been paid by then. My bank does not inform me when a debit order returns. I assumed they would not be debiting since they sent a letter Saying my installment will increase because of the law. On the 8th of Feb I get a call (very rude person it was) Telling me my debit order hadn't gone through. I tell him I know but I don't have money anymore. He insists on debiting the following day. He said he could ask for an extension for my contract of a month. I am not sure where to from here. And I can't have my car repossessed.