What can I say, been through it myself, long story......
In a nutshell
I told them I was building an observatory could you keep lighting reasonable ( no problems they say)
I build the observatory ( they put up 8 .. Yes 8 cheap floodlights)
I take a photo of my yard being drowned in light ( how rude of me to complain they say)
I put in 60 thats 60 leightons green Cyprus trees, close down the observatory, turn it into a mower shed. Scope sits inside while I ponder.
Eventually I bold up and build another as far away from their lights as possible hidden by the house.
We've since had other problems with the neighbors... I no longer care they can rot. Trees are growing nicely , unfortunately their view will be somewhat curtailed.... What a pity.
Have bought a mono camera so I can do narrowband where their lights won't have any effect.
Your neighbors don't and won't give a toss, leave a broken down car on the nature strip, don't mow it and see how they like your life impinging on theirs.
Hmmmm that felt good, nice rant early in the morning. Have a nice day all