CubeCart 4 - Admin Order Entry allow SagePay Refunds

This project is to make a change to an already modified version of the CubeCart 4 Admin Order Entry program. In depth knowledge of the CubeCart V4 E-Commerce system is required and bids from people that we do not already know to be CubeCart experts (ie you have done a CubeCart project for us previously) and do not provide proof of this experience will be ignored. An overview of the changes are : When a admin user edits an order that is either at "Processing" or "Completed" status and that order was paid using one of two SagePay payment gateways (either the built in SagePay Form or our own SagePay Direct) then a button should be shown that allows the user to specify an amount (anything up to the total amount of the order) that can be refunded back to the customer. The detection of whether an order qualifies for a refund is a simple case of checking two database values in the order record, an amount field would then need to be entered and verified that it doesnt exceed the order amount and finally a POST back to SagePay using the correct format and passing the transaction number. Full documentation is available via the [login to view URL] website or can be supplied and a CubeCart store will also be provided for dev and testing purposes.