Being denied for private student loan all of a sudden with my father as co-signer? HELP PLEASE.?

I'm going into my senior year at St. Johns University here in Staten Island New York. For the past three years I have taken out private loans from education finance partners with my father as my cosiginger. They have never denied me. All of a sudden this year I'm being denied. Tried Sallie Mae and they denied me aswell. I have no credit, so it must be my fathers credit why I am being denied a school loan. He insists to me, that his credit is fine and there are no deliquincies. So my question is, who can I call to find out whats wrong with the credit and how it can be fixed? I need a phone number, every place I call just offers to send a copy of his credit report and there seems to be nothing on it that is insuffucient. Please help me out guys, I really want to finish school up and just get this over with. Thanks.