The most common reasons for this are incorrect credit/debit card details, insufficient funds or exceeded transaction limit.
In some cases this is due to the card issuer blocking the transaction for fraud protection purposes.
If you have received a failed transaction notification, please try placing your order again. If the transaction is still unsuccessful, please contact the card issuer (the number is usually on the back of your credit or debit card) and ask them to permit an authorization from Chaos/2CheckOut (our payment processing partner).
You can try a different credit or debit card or contact our customer support team for assistance.
Please bear in mind that sometimes when the payment is unsuccessful the money are not charged from your account and Chaos will not charge you further for the failed order, however the money might be blocked from your account. In that situation please contact your card issuer and ask them to release the money back to your account.