Had the same problem... However the neighbor was a "business" (laser hair removal) that was ina house converted to a business or whatever... ANYWAYS, she had 3 pitbulls that she always just let out (i had a Shi Tzu and a french bulldog at the time...) anyways, MASSIVE turds all the time in my yard, I asked her MANY times to watch her dogs and keeo them out of my yard. The day my son was running around and slipped and fell in a HUGE pile of shit i decided to do something.
I spent about 3 days going to every place i could think of to collect dog shit. I ended up getting a god 30+ pounds of dog shit, I put it all in a 5-gallon bucket and watered it down so it didn't dry out. She was closed on the weekends, monday morning around 5am i took the bucket and just poured it all over her stairs, side walk, parking lot and then got some nice fresh stuff and rubbed it all over the door handles and doors of the house. She was closed for a couple days after that. She asked if it was me and i said yes, it was and net time your ****ing dogs step foot in my yard I am putting a .40 slug in their ****ing heads! Never seen the dogs again....