Hello huaha
I’m sorry to hear that your tickets were charged to your credit card even though you have activated your Half Fare Travelcard PLUS. This issue could be due to various reasons and may not necessarily be a bug.
I suggest you contact the SBB Contact Center at +41 (0)848 44 66 88 (CHF 0.08/min) to report the issue and get assistance with the refund process (if possible). Alternatively, you can contact us through our online form or via chat (scroll to the bottom of the page).
I wish you a lovely day,
Chiara_S