Payment on Trendetna is handled by Stripe. Your card details go directly from your browser to Stripe: they are never sent to our servers and we never store them. What we keep is what Stripe tells us afterwards, which is the card brand, the last four digits and whether it worked.
If a payment is declined
A decline comes from your bank, not from us, and we are usually told nothing more than "declined". The common causes are an international payment your bank blocked by default, a card with a limit for online use, or an expiry date that has passed.
Nothing is charged when a payment is declined, and the places that were held are released. You can start again with the same card or a different one.
If you see a charge that then disappears
Some banks show a pending authorisation before it settles. On a failed or cancelled checkout that pending line usually vanishes within a few days without ever becoming a charge.
3D Secure and one-time codes
If your bank asks you to approve the payment in their app, that is your bank's own check and it happens inside Stripe's payment step. We never see the code, and nobody from Trendetna will ever ask you for one.