I have same issue neighbors cats stray cats all like to use my yard for a toilet tear up gardens etc. I trapped some of them took them to the pound they fixed them and then dumped them back in my yard. So now I trap them and take them and put them in the night box at the pound. Ive tried every type of so called repellent nothing worked ive squirted them with water guns dont stop them cant use a sure fire method since i do live in city limits good luck maybe a dog to chase them out.