Help! Our neighbour's cat keeps coming into our house (and others on the road). Now it's warming up, we enjoy having the back door open to the garden, but he keeps coming in! We love cats, have 2 of our own, but this one is intact and keeps scenting/peeing on any available vertical surface - walls, door frames, table legs. It's vile and stinks. What can we do?! We can't use any of the usual cat deterrents because we have our own. Oh, and also he keeps having very loud yowling matches with another neighbourhood cat below my bedroom window at about 4am most nights...but that's another story!! Any advice?!