Thanks for letting us know how it went. I think that KL/AF is not the only airline who would only sent out an apology to the customer, especially considering the fact that nothing was done at the airport (somehow it seems that they didn't acknowledge this to be their fault, even though it is).

With many airlines, if a problem can't be dealt with at the airport/gate/plane (no matter whose fault it is), then sending a letter often helps but certainly won't always provide you with a decent compensation. This is where bureaucracy really sets in...