Some users who have updated to iTunes 8.0.2 are experiencing an issue in which no movies or songs can be purchased. This problem occurs despite having ample credit users cannot purchase any songs or movies, but also if users are purchasing directly with charge cards.
Apple Discussions poster Bryce Lim writes:
"After updating to 8.0.2, I can't purchase anything on iTunes account. Every time I try to purchase music, a TV show or an application I get the error message that '...due to a problem with the iTunes store I have no available store credit for purchasing...' 'I don't have any store credit, I've been trying to purchase with my credit card like I always have been.'"
For many users affected by this problem, credit on the accounts seems to disappear and then reappear at seemingly random times, which can be concerning to users with large amounts of credit. Luckily it seems the amount of credit is still there, just inaccessible for a while. Additionally, users with gift cards are having problems redeeming them.
If users are concerned about their accounts and the credit amount on them, it is recommended to call Apple directly for confirmation on the credit available. Apple's support is available at this link or users can try calling Apple at 1-800-MY-APPLE. Meanwhile, users can try re-logging into their iTunes accounts to help fix the problem.
Fix: Reset iTunes' account login It appears that this problem might be with how iTunes is logging into the iTunes store, and as such users have had success by resetting their logins to the store. To do this, from within iTunes sign out of the store account, and then quit the program. Relaunch iTunes and sign back in, then try the account again.