Due to recent changes by Mastercard and Visa, you must now initiate a payment of an invoice to update the card on account.
To do this, login at my.xilo.net and view any unpaid invoice on the account. Select "Credit / Debit Card" from the drop down and then enter your new card details in the box provided.
After payment is authorised, your card will now be added to your account and will become the default card on your account.
Note: Please ensure that your account address matches that held by your card company.