iTunes Store: "Your payment method was declined." Last night I attempted to purchase an app from the App Store on my iPhone 4. The previous day I had purchased an app with no issues, and this time was told that my payment method was invalid. When I clicked 'Continue' to fix my information, everything was correct so I re-inputted my credit card security code and tapped done. No, fail, declined.

I called my bank as I am currently vacationing in Ireland, and if my debit card (the card my iTunes account uses) starts getting declined I will have issues. No, no problems, they had a note in my account that I was traveling, and there are no holds or flags on my spending. She also noted that the iTunes store had requested a verification of $0.99 but had not charged the card for the amount.

I returned to the iTunes store on my iPhone and attempted again to input my credit card information. Still declined. I entered a second credit card. Declined. I opened up iTunes on my laptop (OS X 10.6, iTunes 10) and checked my account information there. No prompt about it being incorrect when I log in, unlike on the iPhone which tells me – even for free apps – that my payment method was declined as soon as I input my password.

I attempted to purchase the app from the store on my computer and sync it to the iPhone. As soon as I click on purchase, I am asked to authenticate. As soon as I authenticate, I am asked to fix my credit card information. As soon as I fix my credit card information, I am returned to the screen I was at previously where I elected to purchase this app (in this case, that screen is the home page of the App Store).

Two different cards, no issues with the bank, no way to get it working in iTunes proper on the desktop or through various attempts in the App Store in the iPhone. Any ideas? Any suggestions?
I actually had this issue before too. I am not sure what caused it, but after waiting a couple of days, it worked again. Here are people discussing it on the Apple Support Forums, but there doesn't appear to be a resolution. I think mine may have been a transient service issue or something. It never happened again after this.