by loren_d_c » Thu Aug 14, 2014 2:18 pm
Do you have an example of the error codes returned by your payment gateway when they are declining the cards? If you enable the 'Display Error Details' option in the gateway's settings in ShopSite then when the order is declined it will show the detailed codes/messages from your gateway to the shopper, who can then provide them to you and you can take them to the gateway to ask them why the transaction(s) was declined. And if you have ShopSite Pro 11 sp2 and newer, you should be able to see these messages in the Commerce Setup -> Merchant Alerts feature, too.
-Loren