As a fellow European I can only advice you to get good legal council. From what I can gather from the original article, things are pretty messed up, and there is NO way that you can clear that up on your own. You've got to play the bureaucracy game, or you will have lost. It looks like they are trying to overwhelm you. In Europe employers have a lot more responsibilities towards their employees.
1. Collect all the evidence, in writing as much as possible
2. Don't accept any offers, and don't resign. If they don't want you to show up, make sure that they tell you to that you can stay at home, in writing
3. Get a good lawyer and document the case
4. Have the lawyer write them a letter stating all the points you don't agree with, and propose a large settlement
5. Take the lawyer with you at ANY meeting
5. Be prepared to go to court if needed.
Since this is going on for so long, and is causing you a lot of stress, this is a good time to bite your nails and get it fixed once and for all. Don't let them bully you into anything without legal counsil.
All the best
René