I am pissed

I have to get this off my chest, and here is as good a place as any to carry out my quick rant.
The new neighbours who neither I, nor the other neighbours are very fond of, seem to have workmen working for them, who are just like them. ....."birds of a feather flock together" immediately springs to mind.
On the afternoon that I was leaving home to attend  "Mums" funeral, there was a big blue van parked right across my driveway blocking the entire entrance.
I strolled across the street and asked the workman who was the driver to please come and remove it.
"Sorry 'bout dat....sorry 'bout dat," he said loudly, but it didn't sound very genuine.
He came immediately and moved his van as I had asked.
I left it at that. I thought it was all over.
Even though he is employed by my neighbour across the street, he refuses to park either on his boss's property or on that side of the road. He always parks right outside my wall.
One day last week, I saw him spending quite some time working on his van which seemed to be having a problem.

After an entire morning, he finally closed the hood and drove off.
When I went out to cut the grass the next day, this is what I saw.....

The road was drenched in an oily mess, and apparently he had found it necessary to throw some of the residue on to my grass, thus killing it in the process.
I have decided not to say anything to him, since I may say the wrong thing.
I am holding my tongue, but I am totally pissed.