I would like to upgrade to either premium economy or business using points. My ticket, however, is a sale fare, so not eligible for an upgrade. I have more than enough points that I could have booked a business class trip using points (i was trying to save them). Is there a way around this where I don't have to spend more money, or do I have to deal with it? Is there any chance, at the airport, they will allow me to upgrade? Help?