Figure out and build a working security Access class in c# for a Back end Data Integration project

Amazon's documentation for Selling Partner (SPAPI) is confusing at best. their provided c# SDK for setting up security sucks and as I just found out, either does not work for some REST calls or they are changing rules on the fly and I cannot keep up. Specifically I would like to get a c# class that provides the necessary headers attached to a request for either the standard LWA security calls or the "new" restricted calls This is not about my ability to code, but in taking too much time to figure out all the damn twists Amazon has put in place. This is a new project to replace an existing MWS project in production and the initial deadline is Sept.