You can simply resolve this with the Joyn app:
1. Press the settings icon in the top left corner.
2. Select ‘Your account’.
3. Select ‘My cards’.
4. Look for the card number you want to block and press the block icon to block the card.
Don’t have a smartphone?
Send an email to firstname.lastname@example.org and include the following information:
• The email address of your Joyn account.
• The card number of the card to be blocked.
If you still want to keep your account, please contact us within 30 days via email@example.com. Your account will be permanently deleted after 30 days.