E-Commerce Configuration Guide : Site Configuration Settings : Checkout Settings : PaymentTypeNotAllowedMsg
 
PaymentTypeNotAllowedMsg
Key value:
Any text.
Description:
Message to display when incorrect payment type is used. An additional key in the siteconfig.config file handles situations where a visitor/guest tries to use a payment type that is not allowed. The following key is used to set the message that displays to the visitor/guest in this situation.
See also:
SPType