I have been waiting for apple itunes support to answer for several days since I received their machine generated formletter response telling me they're investigating. Finally after trying everything I could think of I figured it out myself. As suspected and confirmed by Visa, this isn't a problem with the credit card or the credit card information, but an itunes store desktop application bug. First it is displaying a misleading and inaccurate message on entering valid credit card information for an available credit card with more than enough credit (your credit card has been declined). This message implies that apple sent the request to your credit card vendore which wastes your time and the credit card vendor's when you contact them to investigate.
It turns out the whole issue is caused by poorly coded integration between itunes store desktop application and apple store web application. I found an old apple knowledge base article which said that whenever you update account info on itunes store, it automatically updates apple store.
What was really happening when itunes store displayed the CC declined message was that it was trying to update apple store's information to match, but the apple store account info has different options and validaiton than the itunes store accounts info (in my case the apple store doesn't have an option for my country, Jordan). So when a validation error was encountered by itunes desktop app as it was trying to update apple store information, it just falls back to displaying credit card declined simply because the apple programmers did not bother (too lazy I guess) to take the validation error from the apple store and display it in itunes
So what I did was open apple store account management, change my email and save. Then open itunes login with the new email, then itunes will ask me to re-enter account info (not just billing info) this allowed my cc to be accepted immediately.
