Dear agenciesfirst,
I am sorry to hear that you have issues with this plugin.
Of course not all parts are well documented as they exists due to some private rapid coding days.
Whenever I have time I can include more and more documentations. But time is also a problem as it has only 24 hours and my regular job uses a lot of it.
Anyway, if you want to get something pushed (like documentation for XXX) please feel free to raise an issue on github:
https://github.com/ole1986/wp-ispconfig3/issues
Also, fee free to improve it by doing a Pull Request at any time.
I will do a code review and can quickly integrate it, I promise!