Customers can pay their "Due Payment" by login into their account & click on the "Orders" menu or directly from the email invoice.
after clicking the orders menu customers can see all of their order lists from here. in this case #948 is successfully paid the deposit amount now he can pay the due payment by clicking the 'Pay' button.
Not only that, if a customer clicks the order id or the 'view' button then they can see the full details of the deposit like below :
Email invoice: customers will get an email invoice on their billing email address as soon as they paid the deposit amount.
This deposit invoice also has a link for paying the due payment.