If your credit or debit card fails to authorise it may be because you have entered the expiry date or CVV* code incorrectly, please check you are entering in the correct details. If you are sure you entered these details in correctly, but your card still fails to authorise after a second attempt, then please contact the card issuer whose number will be on the reverse of the card. *Note: A CVV code is the last 3 digits on the reverse of a credit or debit card.