Payment gateway notification idea

hi

thanks for interested in my project.

welcome onbored to phase 1 task, i have given more or less the same task to a number of indvisials. you should maximum work 3 hours per day for maximum of 3 days.
your assessment will be based on.
-quality of work.
-efficiency, less hour utilize the better.
-hourly wages

Overview of Project (i.e. online store):
we are a government sector managing service between two entities. and controling product delivery between 1-suppliers/manufacturers and 2-retailiers shop.

Issue need to be solved:
suppliers must pay a retailer a certine bill within 40 days and retailers should confirm reciveing the payment and inform us , so we close the bill. however, retailers dont confirm by email they have receive the payment which cause a delay in closing the bill. despite many of the bill has been closed within a certine time but we dont get informed.

suggestion workflow:
-Suppliers pay the bill through a payment gateway, we get notify automatically once supplier make the payment.

-we can create a page in the website all suppliers can pay the bill through this page and we notified once bill has been payed without confirm through email.

Kindly, we need your only prposal idea to solve the issue with better workflow.

thanks
Khalid