So you booked a ticket, the ticket was cancelled by accident/mistake/lack of knowledge...

But you boarded your flights and you weren't downgraded as you were in premium as in your booking.

The only thing is you lost a window seat for a middle seat (even without an event like a false cancellation, your seat can be change and is not guranteed).

I can understand that as a LT platinum, you'd expect a bit more from AF.
I can understand you'd complain because of the lack of excuses.
I can understand that the sentence "I can't do anything" is frustating.

But why did you waste your money? you had exactly what you paid for...