Premium version has no customer support!

I bought the Premium Version of the Plugin. On the same day, I recognized that the Plugin just integrates a very specific Groups-Plugin, but not Groups in general (which I think was kind of misleading in their marketing). I immediately wrote a message through the support form on their page and asked if they could send me a refund because I thought that the Plugin was doing something different than it actually does.
I never got an answer. I tried it again, but nothing. That is not the priority support they say it is. Sad. The idea is great.