Hi, during the testbox of the Przelewy24 service in the sandbox, after selecting the "Payment error" option, when paying, we always have the same message informing about successful completion.

Please check your Log, maybe you are using the wrong currency, for example, the currency code cannot be ZŁ - it should be PLN, maybe you have a sandbox key that uses in the production server.  If you have still problems please contact with our support.

Regards
Krzysztof

Hello, thank you for the information. The configuration is correct so I am referring to your support