Bill for overusing Microstation

Hi,
I just got a bill for overusing Microstation which is nothing new here in forum. 
I won't pay the bill because that's outrageous. I work alone, have been a user since 1992 and I was not aware of this license disaster.
The bad thing is I don't know who I can call here in Germany? Does anyone have a phone number where a competent person sits on the other side whom I could ask?