Illegal parking on private parking lot

Hello all,

I live in an apartment and have private parking place (documented in mietvertrag) and park my car there, whole parking area is beind a plate "privat parkplatz, kein öffentlicher parkplatz" and a sign with a towing car.

This is the third time during last 8 months when i come back in the evening on Saturday and see that another car is parked on my place, Kennzeichen is from another city. Today the car is really expensive, G class Brabus 😀 When i arrived i stopped in front of this Mercedes with parking light enabled, waited for 20 minutes and because nobody came out to make an excuse i parked on a street.

I do not want to raise conflict from nothing (its really nothing) but it is just a bit pity to drive 650km from south (business trip) and carry my luggage over the street (even if it is the same distance 25 meters).

What German People will do in such situation?

Thank you.