There are many reasons that payments can be declined or payment cards cannot be added to accounts. Banks, Stripe (the Passenger payment service provider) and Passenger Cloud can block payments based on different rules. When a new card is added to an account, similar checks are done to reduce fraud.
Stripe's documentation includes some reasons a payment can be declined.
To check Stripe:
- Log in to the Stripe Dashboard (authorization to access to this is set up by an operators accounts team or management)
- Copy the email address into the search field
- Select the customer from the search results
- Select a failed payment and review the page for reasons provided by Stripe
Additional information can sometimes be found by viewing the logs (further down the page).
Viewing a log entry (especially a "402 ERR") may show the specific reason a card was declined.