Who do I contact for Gateway related queries?

How do I know why a transaction failed? 

When there is a problem with a transaction and the payment is not successful. Chargebee will log the error message we receive from the gateway. 

From your Chargebee web-interface » Logs » Transactions » Find the Transaction

The transaction details can also be viewed from the invoice details page.

Based on the error message you can contact your respective gateway(s) with the error message you have on Chargebee.

For any setup related questions, you can reach out to Chargebee support.

In cases where the issue might need to be taken up with the gateway, the support team might loop the gateway team into the conversation or help you get in touch with them. We will also continue to provide any additional assistance required until your issue is fixed.