I had a PLUS loan with American Education Services (AES) on which we were making quarterly interest payments while the loan was in forebearance (principal deferment until my son was out of college.) For some reason that was never explained to us, AES changed the invoice format on these quarterly interest payments to ones that had a big THIS IS NOT A BILL watermark across it and a $0.00 amount due in the invoice section. However, in very small font above the invoice section, it stated that you could make interest payments if you wanted to... read full review »