Hello Sheewarrea52
Good day…
That is almost impossible, because how to prove that it has not been used? Normally, tickets are not refunded after validity as there are no systematic ticket checks on board of public transit services.
You may try contacting SBB, though:
https://www.sbb.ch/en/help-and-contact/customer-service/praise-comments/complaints.html?stepId=3.17
And, people in Switzerland love niceties such as a hello & greeting in messages. Could be a useful hint when contacting the customer service.
Kind regards,
Roland