Thanks for the hint, will call them. Calling being a much longer process I'll only have time to do that later tonight, when wait times at the Plat line are typically very very very very long (just like on weekends).
Actually, AFAIK Air France is the only airline that does not give customers a choice between a restricted and a fully flexible fare when booking online. Every other airline that I have made bookings with online did give that choice, from the largest like DL and BA and LH to even very small ones like Provincial Airlines flying small turboprops along the St. Lawrence River in Canada. Each one offered the choice between fully flexible and restricted fares either before searching for fares, or when displaying differnent fares available.