I checked in with Arriva by mistake - the checkin looks the same and it’s difficult not to make this mistake.
When I checked out with NS in Den Haag on arrival I was billed again for a check-in. So I was billed 32 euro instead of 12 for one trip. How do I get a refund? My NS trips page says I cannot submit a refund. Can you see the screenshot below?
I was unable to find customer service details for Arriva.