How can one communicate with MFC? such bad service

I'm financed by MFC, I went to my bank to notify them of new banking details and that vehicle payment must be redirected to the new Acc, then month end I get a message from MFC that money wasn't received on the old Acc, then I call them, after a long wait a consultant told me to wait for collections to phone me for new banking details, she said there's no need for me to contact them because they can't change it. Then I keep receiving messages and when I call them again this morning all my airtime ran off waiting for a consultant, aaag this is pathetic these people should know they are dealing with human beings. Its irritating if will deal with such unproffessionalism. Now how am I going to pay for the car really if no one wants to help me?