Ofcourse directly by email or mark @Nanja  as she is the Community Manager and she can connect you with the Customer Service department.

A direct mailadres would be great. What is the mailadres of the customerservice?

 I used once this email address and got a reply within 48hrs (removed by the moderator)

Hi @mandarijn 

We encourage you to contact us via our Socials, such as Facebook, Instagram or Twitter. Otherwise, you can send a request through this link: https://eurail.zendesk.com/hc/en-001/requests/new