The cap of the visor Opel Astra J is a common problem. To remove the creak, remove the visor of the dashboard. He's holding on to four steel clips. You need to grab him behind the back and pull it on. It's going to take a lot of effort. Once the visor is removed, it will be necessary to remove the bolt attached to the retaining cap. A raspberry (soft adhesive material) will be required to remove the creaking. They need to pluck all the pros under the visor. In the area of contact the visor with the top of the instruments also needs to be applied to the madeline. The back part of the visor is to be slated by a madeline on the perimeter. Madeline needs to be taped so that when the visor is installed it is not visible from the outside.
The assembly is in reverse order. It's important not to forget to spin the visor.