I'm sorry not to sound sympathetic, but how exactly do you take out PPI without knowing, especially when it is added to the amount of the loan, or deducted from the proceeds of the loan?
Frankly, anyone daft enough to buy something (anything) without noticing it, or daft enough to buy an insurance policy that doesn't actually cover them, deserves to be taken to the cleaners.
And, if the money is to be refunded, I think it should go back to the original lender to reduce the debt (and interest charges) rather than going back to the borrowers who will probably only fritter it away anyway.
And if you are in arrears, that is doubly so!
Anyway, I'm a nasty, unsympathetic bastard. get over it and move on...