Hello Huettoonnu94
Not sure who has told you to use an e-mail address to request the ticket refund. SBB cannot be contacted by e-mail.
Provided you had purchased the Swiss Half Fare Card from SBB:
Simply use the search engine of your preference and enter keywords ‘SBB refund’ and the search result will be this website
https://sbb-tickets.cc/en/help-and-contact/refunds-compensation/refunds-compensation.html
offering this refund request form
https://sbb-tickets.cc/en/help-and-contact/refunds-compensation/refunds-compensation/refund-form.html
There is no guarantee that your Swiss Half Fare Card will be refunded. As a rule of thumb, tickets that are or were valid are only refunded if you have a proof of non-use by some train staff.
Kind regards,
Roland