I'd advise you to do the following:

- Go to the AF or KL website and log in with your FB details
- Perform a miles search for flights GOT-IAD for the day you were supposed to travel
- Report to us here what options are available for a "new" FB booking. You should be able to be asked to move onto any of those trips.

It's highly unlikely that there are no alternative routings ready to go in the FB booking tool not only for the day you originally wanted to travel, but also on the day before. But you don't have to accept travelling on a different day.

I just had an FB cancellation last week, and again they just moved me to the same flights on the very next day, as they always do. This does not mean you cannot travel on the day you wanted to; I have never failed to be rebooked on the date I wanted when I rang up.

(You won't be fobbed off as easily on the phone next time you're told there's nothing available, when you have the FB booking tool open in front of you showing all the options that are available. And it doesn't matter what the price in miles now costs; they have to rebook you)