So, I want to add in short my story with that module and my first experience with the Nextendweb support team.
I own that module for more than 5 months and I had some problems with it. So I decided to contact the Nextendweb team for a first time. They not only upgraded to newest version, but they also fixed my issues within 2days! I have to make clear that they had not been obliged to help me, since I have not an active subscription to them. I have been really impressed by the Nextendweb team and their willingness to help without a second thinking.
I strongly suggest the Accordion Menu.
Thanks once again Roland and Daniel!