Autom. or Manual Level Control?

So, since I haven’t gotten smarter in the meantime, even though I’ve read almost everything about level control, I’m asking for your help. I have an Omega B (FL) V94 Bj 10/99 2.2l 16V. For some time now I’ve noticed that the vehicle is sinking at the HA, but not going into the corresponding basic position. In the forums it is advised to put something heavy in the trunk so that the compressor lifts the car at the HA. Since I weigh significantly more than a suitcase, there is enough weight. The car does not lift a millimeter and a compressor noise is not heard either. Only during a braking process my xenon headlights stand up or down. A headlight setting at the light switch does not have the car. Lt. Indication of the FOH is rather rare that the shock absorber of an Omega B ( FL ) covers up. He would suggest that the air in the shock absorber has to be refilled. Since when kan n one to fill shock absorbers with air?!?!!! *fully confused!!* I have been looking for a valve in the trunk in vain until now, unless I have overlooked it. Is there a more precise indication about the seat of the valve or with what pressure you have to fill it up? Or, or or or………. Has someone already had experience with costs of repair? It would be awesome if one would come here to say hello Opel test driver