i have 3 cats, 2 of them cant go outside so i have to have litter trays. my eldest cat (3 years old) pulls and claws the liner everytime he uses the tray leaving lots of big holes in the liner and pulling it over his poo so the poo goes on the liner meaning i have to change the whole tray everytime he uses it. none of the other cats do this. i have tried a deeper tray, using more litter, less litter, taping the sides of the liner to the tray, using shallower liners and rolling the sides down to the level of the litter but nothing works, he still destroys the liner everytime. any ideas for getting round this problem?