Even if you had enough miles in your FB account to request an upgrade, L and T fare would not allow you to upgrade using miles. For tickets purchased in the US, you require a minimum of K fare and above to upgrade (award seat availability "O" is another issue).
http://www.klm.com/travel/fr_en/flyi...ward/index.htm
Paying for an upgrade on AF flights, I have neither had this experience nor heard anyone being able to do so (meaning it could be difficult or impossible to do so). But give it another day, some of us on here may be able to share his/her experience.