To add a billing card to your MailBluster Brand, go to your your specific Brand and then click on Billing > Payment methods. Then click on Add new.
Select any one of the payment method: Card or Bank from Add payment method. Then click on Add payment method
After entering all the card details, click on Add payment method and your billing card will be added like this as shown below.
If you previously added any billing cards but did not show up here, then you need to click on manage these legacy cards here.
Here is a list of billing cards that were added to this brand before.