You need to go to the Customization Manager and update the VersionBillingManager from 126.96.36.199 to 188.8.131.52 and save the change. The Billing Manager will work after that. You might have the same issue with other items such as the VersionWebPlaform. or the VersionDatabaseManager key. You will need to update them to 184.108.40.206.
If you are on a shared drive, all sites need to be updated to 220.127.116.11 for those keys.