Order list in public store is extended to provide info for orders with payment plan. On order details page customer can see payments, their amount and statuses. Customer can also change payment plan according to site rules.
Additional feature is “Edit Order” page which provides a possibility to edit quantity of ordered goods, merge shopping cart with order. After saving order customer is redirected to edit payment plan page to see and possibly change redistributed payments.
Order cancellation asks customer for reason and shows the refund amount he will receive (amount paid excluding transaction fees)
Data layer has extended order table, payments table, payment plan table and reasons for on-hold and cancellation processes.
Admin part of plugin has an element of creating .csv file with payments to submit to bank. This process is secure, because no payment info is submitted (customer enters it on bank site). After receiving bank response there is a function to process declined payments. Also there is a scheduled task for daily automatic processes.