I could understand overbooking BE/FC according to an algorithm that leads to rare oversells, but it would be reassuring to know what the rules then are to prioritize revenues passengers for downgrades. Do they first seek volunteers? Is the order based on elite status, ticket fare class, or what? If someone is downgraded, what is done other than offering then a (horrible) coach seat on the same flight and refund of the difference in money/miles? How are refunds calculated? Can people be booked on partners or other airlines? Does being on an award ticket matter for rebooking? Can one refuse to board and get a complete refund? Can one wait for the next BE/FC seat on a DL (or partner?) flight?