I am very displeased with Air France as well as other airlines for creating a defensive system that sucks money out of users when I have paid to have my seat reserved.

I thought the implication of this answer was that perhaps my desired seat assignment was not possible. Online check-in allows blocks where others cannot assign seats, but they charge a separate fee for this.

I asked if it was possible to change my seat assignment to one seat space during online check-in 30 hours prior to departure, but the Air france replied that you have to check yourself if it was possible on a day when online check-in was available.

and I asked if it was possible to change the reservation to make one seat available, but the response was that it was impossible to designate the seat you wanted because of the “compulsory adjacency” rule.