Ask HN: place to get 1:1 help with specific development issue?

I am trying to do some P/Invoke stuff in C# to call a C++ .dll; I have no .h just a .pdf with description and I need some help (AccessViolation probably due to wrong signature of something).

The issue is way to specific for Stack Overflow (tried anyway: http://stackoverflow.com/questions/41127575/system-accessviolationexception-after-p-invoke-missing-info ) and random IRC channels are no help; any suggestions where I could find a fellow developer with enough C# and C++ experience to help with the specific question?

I don't mind if it's a paid option; just really have no idea where to go to move on with the project.

Thanks in advance.