Hi Bjoern,
Please be careful asking for, and taking advice on a problem like yours from people online. With all due respect, your current understanding of roles appears to be somewhere in the region of zero, so attempting to follow advice from anybody who is trying to help you - based on the information you have provided - could easily lead you to cause all sorts of problems for yourself and/or your employers.
The only bit of advice you should really be getting in response to your question is that you need to either pass the problem to someone who knows what they are doing, or get yourself trained - in which case check out the ADM940 course.
Sorry to be blunt, but there is no other sensible alternative.