Maybe print thi page and show it to the klm agents? (Page was updated 28th)
KLM would just rebook you to the next available flight, despite human error on their part. Unfortunately EU261 denied boarding clause only applies to overbooking.

https://www.government.nl/topics/cor...ion-categories

You are travelling through the Netherlands to a non-EU/Schengen area country. You must prove that you have a connecting flight to a country outside the Schengen area. The connecting flight must depart within 48 hours of your arrival at the airport. You must not leave the airport’s international transit zone in this period. Please note: the United Kingdom (UK) is not part of the EU/Schengen area.

if you want to book elsewhere the better option is Turkish airlines IST GRU nonstop.