If you have only misplaced your card, you can temporarily block it on the App to prevent any new charges being made on your card:
Tap the Card tab
Click on Block below the picture of the card
A pop up will ask you to confirm this action – click Block to proceed
This action is reversible, and you can unblock your card at any time. Once you unblock your card, you should be able to use it as normal.
If your card has been lost or stolen, you must cancel it on the App to prevent any fraudulent use:
Tap the Card tab
Click on Cancel Card
A pop up will ask you to confirm this action – click Cancel to proceed
This action is irreversible, and your card will be cancelled. At this point you will need to request a new card.