pure revenge a colleague once suggested to me that p!ssing into a super-soaker water pistol and shooting them with that was very effective. I think his expression was "even if it doesn't stop them, at least you have the satisfaction of knowing they go home and rub p!ss all over their owners house" lol
Layan inch coco shells all over the soil, you get a big bag from homebase for not much - they don't like the smell.