Sorry if this topic has been done before, but AAARRGGGHHH!!!
Our neighbour's cat is always coming and pooping in our garden! It stinks! How come there are byelaws stating that people have to clean up after their dogs, but cats are allowed to roam around shitting wherever they please??
If you've got older DCs I'd buy them super soakers and tell them that they are to use them every time they see the cat in the garden. I'd also try speaking to your neighbour and ask if they can try and make their cat use a litter tray. You are right, there have been threads on this before and they usually turn nasty. You do have my sympathy though. Cat poo is disgusting and I hate it when I find it in our garden.
God your neighbours are so irresponsible. Everyone knows how easy it is to toilet train a cat. I bet they havent even tried any of the books, talking to it or drawing a picture of it crapping in your garden with a big cross next to it. Thats how I stopped mine. Thier language skills are basic, but they totally get stuff if you draw it for them.