3DS/Safekey

My payment was rejected, how can I proceed?

1. If your card is not equipped with the 3DS/Safekey: please try again using a card which has this system.
2. If your card has the 3DS/Safekey system:

Please try again after at least 24 hours.
If you have a customer account: try registering your bank card before booking.
Book over the phone on +33 892 35 35 35 (international call rates plus any network charges may apply).

上記条件を満たしても、またはいくつかの提案に従っても駄目なら、最後は電話でしょう。

でも、
How can I book with PayPal?
You can pay by Paypal for all SNCF non-exchangeable and non-refundable tickets (excluding iDTGV, OUIGO and Italo) and if you select an e-ticket, Ticketless Thalys, Print@home Eurostar (depending on carrier) or Home Delivery.
という方法もあるので、カードに見切りを付けることもあり、でしょう。