Hello,
I am trying to buy the Half Fare card on sbb.ch website for me and my wife but it gets stuck on the payment stage (after I enter my card details and click “Make Payment”). Attached is the image of the error message.

I have been trying the entire day today but it is always stuck at the same page. We are reaching Zurich on 22nd June. Any assistance is greatly appreciated.
Best Regards,
Laxman