We won't know if we don't try
I just spoke with a woman who is complaining of cats coming up to the tenth floor and defecating. She said that her neighbour has seen a young woman with long hair taking the cats up and down via the lift. I asked if she knew whom this was and where she lived. The woman was reluctant to speak to her neighbour saying it might make relations worse. She also had no idea where this woman came from.
The complainant also said that she had been using mothballs since the town council suggested she use them and that worked.
She said she had another neighbour downstairs who had several cats. The flat was filthy and complaints were made. The HDB came down, and after two months the cats were removed but she said the cats had been moved back in. She said there was no point speaking to the neighbours.
I told the complainant we cannot assume that people will not listen. There may be a chance they ignore what is said, but we should give it a try. At the worst the situation does not change. At the best, they may change their behaviour and the nuisance will stop. I pointed out that this woman she has seen only lets the cats out late at night - she may think this is so it won't disturb the neighbours. She agreed.