Not wanting to assist with online banking reversal

I have requested my homeloan debit order to be changed from my chq to my savings, they confirmed that would take a month and would only be done as of May 2015. Just to discover it went off my savings acc putting my account in a minus balance. Trying to rectify by transfering funds from my chq to my sav, by accident selected my credit card instead. Phoned online banking, credit card div and all agents said no reversal can't be done. This has caused to put me out of pocket completely and all my debit orders will be returned. Its just unacceptable that this cant be reversed. I need urgent and proper assistance please!