sim.plified.com

On my installation of Magento, I wanted to return the user to the payment screen when their card was declined.  This is a bit of a hack, but it does work.  I simply inserted some custom JavaScript into the opcheckout.js file which is located in /skin/frontend/default/default/js/

I searched my error message for the word "declined" and based on that, push the user back to the payment screen just before showing the alert box.

if (msg.indexOf("declined") > -1)
{
     checkout.accordion.openSection('opc-payment');
}

I insert this around line 760, right before the "alert(msg)".