An anecdote about the cost of a reward seat.Two years ago, I was travelling on a reward D class seat YYZ-FRA-YYZ. A few days before departure on the outbound, I received a call from AC who wanted me to give up my inbound portion D class seat. They gave me a J seat on LH and they threw in an MCO for $500 for the inconvenience. I always wondered why they needed that seat so badly.