You can change your payment method by logging into your My Account area: https://account.iljmail.com/my-account
Then you click on “Payment Methods” over on the left menu.
You will see something similar to this:
Click the Add payment method button to add a new card.
Once you add the new payment method make sure you make it the default or your payments could still fail.
Note: The only way to delete a payment method is to add a new one first.