Christian, This is a common problem here.
I highly sugest reading reviews and support forums when purchasing plugins. there are some amazing Developers on here who will do anything they can to help you but there are also some developers on here that have no intention of supporting their products at all.
The best you really hope for here is help and advice from the community.
As developers go I can paticularly recomend Sean, Senior Developer, Dave and more recently Artmedia too.