All of the plugins on Wishlist Member Store have been developed by HappyPlugins or a 3rd developers as for that each plugin developers has there own support help-desk.
Saying that we are not the one that need to contacted if you need support for a products that you have just purchased.
Contacting the Support Departments
Here is a list of the support desk address for each company
How do you know who behind a specific plugin / product?
This one is very easy, just to go the product page check for the relevant information under the specification tab.
There you will find all the information including the plugin the developer.