Currently, the 'Customer on account' module in the eCommerce checkout is not meeting the client requirements and leads to a clunky user experience.

Problems with current state:

1. It is possible to change the amount (the majority of clients is requesting 'all or nothing')
2. It is necessary to apply the amount (The customer only wants to select 'On account')
3. It is necessary to trigger a 'Save' of the payment module infos
4. As the payment module is the last step in the checkout, the customer needs to perform 3 actions at the end of the checkout process, without any additional user input (Apply, Save and Place order).

My suggestion is to make the 'Customer on account' module more user friendly by eliminating the Amount input, the apply and the save functionality. From my experience in commerce projects it is required to 'Select' the Payment method 'On Account'.

A simple radio button, similar to the selection of a delivery mode will fulfil the requirements of all our customers which are using 'On account' as a payment method.