I was incorrectly billed 12 euro for a trip from Amsterdam Central station to Amsterdam airport on 1 September. I have received an e-mail suggesting to call you, however I am abroad. In my OV card history I can see the message saying I cannot claim back a missed checkout fee because I have NX Flex subscription. I am not sure I understand? Can you adjust the fee? I am sure many people miss check-outs at the airport as there you need to remember because there are no obstacles when getting out of the train stop inside the airport.