Neighbour cat pee at my balcony

Pretty much your neighbors are right, there really isn't much they can do. The cat is pretty much marking "its territory" and you happen to be in it. Most pet stores sell products that will keep a cat from urinating on certain items. If the cat is an unfixed male it may be spraying (which smells and looks like urine but much stronger) which I am not sure if these products would work on that. Also you could try using heavily scented citrus products around your balcony. Especially in the spot that you have noticed the cat urinating in the most. Good luck with the pee problems. mahmah