You may receive an error like this when trying to purchase or update your billing information:
Error: Oops! The following items appear to be invalid:
Can you please take a screenshot of your console.log (right click, click Inspect, click the Console tab then refresh the page)? Also, if there are any errors under the Network tab, please list those as well.
Can you try the purchase again then view your Java Console? Then you can copy and paste the information you find there into your reply so we can see if there is something there to explain the trouble you're having.