Opencart Subscription Module - Changes Required

We have an opencart store and have purchased a product subscription module as available from opencartexpress. How it works currently: Currently, the product subscription module allows us to sell a product as a subscription with a specific duration (e.g. 3 months) attached to it. When the subscription duration (e.g. 3 months) expires, then it enables the customer to renew their subscription again for another period (e.g. 3 months). How we need it to work: The product subscriptions need to be able to be broken down into a set number of days (e.g. every 30 days). So, if we create a 3 month subscription @ $20pm , it must require the customer to make 3 equal payments of $20pm x 3 months. One payment every 30 days until their subscription ends. Then, every 30 days (example), a reminder and order/payment request must be sent to the customer via email with a link back to the original subscription product. On the product page it must then show the customer how many months is remaining on their subscription and then allow them to re-buy the product for the following/next month's payment and so on until the subscription ends. Also we need to have a "subscriptions" link in the customer's account section to manage their subscriptions which they have purchased (if they have). (We will need to have a clear record of the specific files which was changed or added – So that we can implement it again if we need to upgrade opencart in the future) Background Info To view the current product subscription modification, please visit opencartexpress and the product link at: [login to view URL] This will give you an idea to see how the standard product is already setup and what modifications you will need to do in order to make the changes as required (above). Important Note: Only developers with specific experience in working with the opencart platform must apply. Seeing that we have the product subscription module already installed and working, you will only need to make minor modifications and add some additional code to get it to work as requested.