Hello k2pooh
Supersaver tickets can be exchanged or refunded up to 30 minutes after purchase (if purchased while logged in). After this time, no exchange or refund is possible.
If you have a Supersaver Flex ticket, you can get a 50% refund up until shortly before departure. When purchased using your login, you can do this yourself. When purchased as a guest, a form will be needed.
All information is available here.
I wish you a nice weekend,
Chiara_S