I've had this rate change happen to me as well; glad to find out why now. The other thing I've had difficulties with is when I rent a car personally, using a personal card, but the charges revert back to my corporate card. After the third time I had to show my manager that the receipt I received had a different number on it than where the charges were applied... (I've never claimed to be good at the internets). I guess I'll continue to watch closely.