If your card is missing please lock it in-app. This will prevent anyone from using your Curve but you can unlock it if you find it again.
Tap the menu on the bottom left, then slide the Lock Curve button. ( If your app doesn't look like this, tap the top left menu, select "My Curve Card, Lock Card". Then upgrade to Curve 2.0!)
Choose the 'Curve' menu on the bottom left of the app, then tap on the Lock Card button.
If you don't have access to the app and have misplaced your card, please call our emergency lost and stolen phone line: +44 203 322 2585.
If your Curve is gone forever, message one of the support team in-app or email email@example.com so they can cancel your card and issue a replacement (free of charge).