Firstly freeze your card if you have access to your phone as this will stop anyone using your card from that point onwards.
If you are certain that your card is lost or stolen, then report it as lost/stolen in the HOLD app.
If you don’t have access to the HOLD app, then please contact email@example.com and request that your card be cancelled because it has been lost/stolen.
Once your card is reported as lost/stolen the card will be cancelled and it cannot be used again. A new card will automatically be issued and sent to your address associated with your HOLD account.