These are thus only valid with also a valid pass(day). I think there are some fb forums/groups to excahnge, but as I myself never do fb, others may know more

It is possible to request a refund, as long as you request it *before* the date of travel. 

To cancel reservations, please go to your reservations overview and click on the trash bin icon next to the unwanted booking. This will cancel reservations for all seats on the train in question - it is not possible to process partial cancellations if you have booked multiple seats on the same train. After you validate the cancellation request, you will receive a notification showing whether or not this reservation is refundable (and the corresponding amount), prompting you to confirm your request. The cancellation process is automated (which means it is not possible to request changes after you confirm it).

In the event that a refund is offered for the reservation, please note that e-tickets and paper tickets are processed differently. For E-tickets, the refund will be processed automatically. For paper tickets, you will be provided a return address to which you will need to send the tickets. Once the paper tickets are returned to us, the refund will be processed and you will receive a confirmation.
If you receive an error message or are unable to see the reservation in your overview, please let us know as soon as possible.