How do you get a car towed out of an assigned parking space?

This was happening at 4:45 pm today. The space is assigned to me. Someone in an adjacent building, not part of our apartment complex, likes to park in my space. When I call the tow company on the signs in the lot, they tell me I can't call for a tow because I'm not the complex manager, just a tenant. So, now this vehicle gets to park there until they either leave, or someone in the manager's office shows up for work tomorrow???

I have already spoken to the driver of the vehicle. All she ever says back to me is, "Call my lawyer." Well, who the fuck is your lawyer? This is the 3rd time she's in my space. Now I think she's doing it just for spite.

What would you do?