This is always an unpleasant situation for both the customer and us. The first thing to do is to try again in a few minutes, as this may be a temporary problem. You can also try another payment method if possible. If neither of these helps, please email us and let us know which payment method you are trying to use. We also usually receive a notification of a failed transaction, so we can contact the payment processor for more information and hopefully they will come up with a solution. You can also ask your bank for advice.