To add (or update) a debit or credit card to your Services account you would do the following:
1. Browse to https://www.blackmoonhosting.com and click the Client Log In menu.
2. Click the green 'Secure log in' button under Services & Billing.
3. Log into your Services account (Forgotten your password? Reset it here).
4. Click on the Billing > Manage Credit Card menus.
5. Now simply enter your new credit card credentials and click Save changes.