If you think you have mislaid your card, here's how you can put a temporary Freeze on it:
Log in to Freeze your card by clicking the button below.
Select your Credit or Debit card, and select Freeze Card.
You should only do this as a temporary measure. When the freeze is in place you will be unable to use your card.
If you find your card, follow the steps above but select the 'Unfreeze Card' option and use your card again as normal. If you can't find your card, you should cancel it straight away by reporting it as lost/stolen online.