At our rented offices, we have a number of spaces allocated specifically to us, which we have put signs up on each of the spaces. We have been here for many years, so its not like the car park has changed recently.

It's just enough spaces for my staff and our work van.

What can I do about people visiting other businesses, who have no spare spaces so just dump their car in one of our spaces, ignoring the signs.

Yesterday, I left a polite note on someones car. When they returned 4 hours later, they wrote "Go Do One" at the bottom of the note and chucked it out of their car window.

I could tow the offending car out of the space with my defender, but I am guessing thats probably not sensible.

Are there any sensible things I can do?