Inconsiderate neighbor

I wrote a while back about the jungle in our lawn due to the 'love of planting but lazy to maintain the plants' attitude. That problem has been solved by me chopping off the unwelcomed plants.

We have another problem now. A very smelly problem. You see, they have tens of cats kept as pets. While I don't hate cats (although I am quite allergic to them), I really HATE (in bold AND capital letters) their leftovers aka poo poo aka litter! ESPECIALLY when they left them all in my lawn and backyard!

Excuse me CATS and CATS' owner. My house is not your/your pets' toilet!!!!

I had plans to grow a little vege and herbs garden behind the house, but because of the severe problem, now I am seriously thinking of putting cement all through the backyard so that the cats cannot litter in my compound. And that involves more $$!

Seriously, I don't have anything againts you keeping as many cats as you wish (or other pets for that matter) But, please keep them in your part of the neighborhood, not on somebody else's. Please be considerate.

Currently, my day job includes disposal of cats' litter and it's really not pleasant at all! Flies are threatening the house terribly now and we couldn't have any meals without the agony of the smell and the flies.

Now, do tell me how do I end my misery? I just couldn't wait until their new house is ready (currently under renovation) so that they can pack up and leave with all their pets. But we seriously don't think that they will bring together all the 20+ cats that they have, so if there are any cats left later, I will personally take the liberty to dispose them to the SPCA or something. I don't mean to be cruel, but it would be so much better than some other bad thoughts that I sometimes have while disposing their poo poo! heheh!