Check out confirmation

For V1.4.9.3
My payment work through Paypal.
I denying payment if "unconfirmed address"
When customer try order with unconfirmed address credit card, checkout confirmation page is didn't give any notice and when click "confirm order" stay same page just shows please wait.
How can I add notice to customer like "Try different credit card" or "Please use verified address credit card" or any thing notice to customer processing is not through because the using wrong address credit card.
Is there any extension for that.
Please post here, If anybody have any idea.