You story is hard to believe. You state that you were due to fly ZRH-AMS on Thursday and that KL flew you on Saturday (2 days later)?
Unless there were some special event affecting AMS, this seems weird.
KL has six flights a day and there are quite a few other operated by other airlines.
Even if no nonstop flights were available, they could have rebooked you with a connection.
Maybe you are talking of a week when there was an ATC strike or a heavy snow storm
, but under EC261, the airline has the obligation to reroute you at the earliest opportunity.
I am notdoubting your version, just that KLM seemed not have have made a big effort to find a reroute.