Desk top Application development for additional feature to current system

We have an application that is developed in Visual Studio 2010, VB.NET, MS SQL and many PHP scripts and licensing protected with CryptoLicensing for .NET. The application enhancement needed is: 1. Add sms facility to integrate with a 3rd party provider platform (API) 2. Add functionality to the application user panel 3. Add database for sms rates (2 groups with countries in the groups) 4. Purchase button for bundles i.e. $10, $20, $30, etc. to added with PayPal checkout 5. Reduce balance as sms's are used per group 6. Block sms when funds reach 0.00 and activate again when credited and paid Budget just an indication and not hard and fast.