Your moan is echoed here. I got blatantly "bounced" off a connecting flight years ago with KLM - denied boarding and compensation due under EU law. Did they pay ? Did they hell, in all they gave me three reasons why I could not board and in the course of time I took this to the CAA people who enquired and got one change in explanation (version 3) and ended up telling me that they did not have enforcement powers so could do no more for me. A question was raised in the European Parliament where my case was among those cited - that disappeared into the fog. Then a while back I learned that the Netherlands had set up an enforcement office - presumably because KLM have given rise to an enormous number of howling complaints (their reputation on these matters is very poor indeed) and perhaps as a result of EU pressure (might my mention there have helped just a little ?). That office replied that my complaint was based on events that were too old ("timed out"). They, as all the other partiers I took my complaint to, pointed out that I can raise an action in my local court. KLM are among those airlines which rate particularly poorly, and you are correct, they are in a class with Ryanair when it comes to attitude toward their passengers. I have flown a lot since the event in question, including long haul, but never with KLM and I will not do so again either. The only dealings I will have with them in the future will be in court. One thing was that everyone (including KLM staff, incidentally) did say that I should insist on cash compensation and never let myself be fobbed off with a voucher (they offered me "a gift"). The trouble with vouchers is that the issuer (KLM) is entitled to dictate everything about them, including their real worth and all terms of their use - as you have now found out to your cost. Having had the due cash compensation, it might actually have been better to bin the voucher and fly cheaper with someone else, certainly free of the niggling unpleasantness that is bound to linger toward KLM.