An unexpected error has occurred. Your purchase has not been completed. Please contact Steam Support.
This error can occur when our system has encountered an issue with the transaction that you are attempting to make.
Test the issue once or twice more, ensuring that you are entering the correct billing information. Avoid spamming failed purchase attempts more than a few times.
If you continue to encounter this error, please contact Steam Billing and Support with your Steam account's login name and we will assist you further.