Fixed mine, dunno why it broke tho?
1. Go to: store.apple.com/ca (or store.apple.com if you're in the us)
2. Click account in the upper right corner and then click change account info and sign in using the same email and password that you use for itunes store
3. U R now on the account profile page. Remove ONLY the credit card numbers from the card number field-DO NOT remove the expiration date or credit card type.
4. Select where you are primarily going to be using your purchases (ie-home) from the pop up menu near the bottom of the page.
5. Click continue. If you are asked any other information, be sure to click continue after making the updates so that your changes will be saved.
6.Now go to: phobos.apple.com/accountSummary
7. Sign into the iTunes store using your account name and password
8. On the apple account information page, click the edit payment information button
9. Choose "none" for payment method and click done to save your changes.