No sweat! You can temporarily freeze your card anytime in the STACK app > Settings > Freeze Card. Once you're back in Settings, you'll see a pink banner across the Settings menu saying "Card is temporarily frozen." If you think your card is just temporarily lost and you find it, you can unfreeze it in the app anytime.
If you think your card is permanently lost or stolen, freeze it in the app and then give us a call at 1-877-STACK-01 so we can help you out.
If you don't have access to your app, give us a shout at 1-877-STACK-01, and we'll be happy to freeze it for you.