Originally Posted by
mikeyyz
I just had an interesting thought cross my mind...
Currently on a trip where they paid full-fare J for me ($11k r/t, painful!) - on my way back from LHR-YYZ, that segment alone was $3,700. Can I get them (at the airport, LHR) to downgrade me to M, use a cert, and then get an MCO for the $2,700? Or would they have to refund fare difference to the travel agency.
Anyone ever done this? I'd prefer to salvage some of the value for myself

Not an answer to your question but a comment.
Not sure where you were going and if this could have been a possibility but for $11,000 you can get a First Class RTW ticket = a much better value for $11,000 plus the extra points.
I believe a Business Class RTW is about $7,800.