As soon as you notice that you've lost your card, please report it online.
In the 'Cards' section, select the card you've lost and click on 'Report lost / stolen' at the bottow of the right-hand side tab.
Select 'This card has been lost' and enter your password before to confirm. Please be aware that this is an irreversible action that will definitively block your card.
We recommend that you check your recent transactions to make sure that there has been no fraudulent use of your account. If you have any doubt about a transaction, please report it.