AF has changed my seat selection
 

Have you requested your seat refund?

Is that an award ticket ?
Even if it is, FB is not handling customer complaints. They have to go through the usual way using the contact form on-line.

All airlines will say this - all seat request and assignments are not guaranteed...

Thie is a slightly different case, though; the OP has paid a higher fee for a particular class of seat for which the airline has now confirmed they cannot provide.

The seats that the OP's party have been moved to cost less than what has been paid by the OP's party.

Again, per AF's General Conditions of Sale for Seat Options:

as well as AF's own General Conditions of Carriage:

No one says OP is not entitled for a refund. In fact, what OP is entitled is the refund.

Also - to be clear, per AF's own literature, the duo seats are not actual separate classes of service.

They shouldn't have.

Make sure they refund you for the 2 seats paid for and not provided

Of course they are not a “separate class of service”. As stated above, these seats require a payment considerably higher than standard seats.

While the airline reserves the right to change seating assignments, they do not reserve the right to reseat pax unilaterally in “cheaper” seats.

Seating changes and moves within the same category of seat can happen, but seating changes that result in a move to a “cheaper” seat should not happen.

There are conditions of service and there is customer service. Of course, airlines will always deny liability based on both valid and silly reasons indicated in the contract. But I believe they should do something to make up when they screwed up. It is always easy to put the blame on passengers and never take a blame when you screw up.

Why presume that AF "screwed up." This was more than likely a conscious and affirmative decision by AF to move OP. This is hardly confined to AF and OP expressly agreed that this might happened (look at the contract he chose to agree to). Neither AF nor any other carrier with any sense is going to explain its reasoning and it is highly unlikely that any front line phone agent knows or could find out.

He is entitled to a refund of the additional fee he paid. That is not a customer service, commercial or any other gesture. Rather it is a refund, exactly as AF calls for,

If I were OP, I would not seek that refund now. If seats he wants open up between now and his flight, perhaps he will want them. After he returns, he can then make a request for the refund if his primary desire, the better seats, is not fulfilled.

But that *IS* the screw-up: consciously and affirmatively "screwing over" the OP by turfing them into cheaper seats after having collected payment for these seats.

Big joke. Don't tell me, in any serious IT system, that data updates are not traced, I would not buy it any second. Conscious and affirmative decision? More like an IT glitch!