go to local zoo and get some tiger poo,it will keep cats away.a mate of mine kept picking it up and put it in an old bucket with water in it he then set a trap and captured the cat in a box and threw the bucket contents all over the cat.it didnt come back and think about when the cat snuggles up to its owners.another idea is put cat in boot drive for about 20 miles and kick it out,and it wont find its way back