Hello T.Dubya.B
The date cannot be amended, you have to cancel the pass and repurchase. You can simply ask for a refund using this form:
https://sbb-tickets.cc/en/help-and-contact/refunds-compensation/refunds-compensation/refund-form.html
A CHF 10 administration fee is applied for each refund request.
I, personally, suggest you to work with the month’s name instead of numbers, to avoid confusions. Here in Europe, we do not use the date format mm/dd, yet dd/mm. Thus, here, 05/01 is understood as 05 January and not 01 May. However, when you write 01 May or May 01 is clear to anyone 🙂
Kind regards,
Roland