Owncloud Billing and User creation Automation

We are a cloud storage company, based in India, providing customers cloud space on rent (storage as a service) using Owncloud open-source module. We need to automate the Billing, User creation, & management , Email notifications. Everything, from new user creation to the changing/cancelling storage plans, needs to be automated. In short, we need to integrate and merge payment gateway (We are using CCAVENUE payment gateway) and owncloud module , so that a all operations of cloud storage are managed automatically, just like "Owncloud HostBill module" or "Owncloud WHMCS module". These above are ready to use modules used for automating the billing the user creation for Owncloud. Need to hire people who expert and experienced in developing custom owncloud apps written in PHP, and good working knowledge of PHP, MYSQL and payment gateway integration . Further details will be discussed once we shortlist and award the project.