I recently bought chai from the office canteen and the cashier gave me some toffees as change. When I held the toffee packet, it felt empty even though it was sealed. Can I take legal action against the toffee company?

You may not have a strong legal case against the toffee company. You purchased the toffees from the canteen, not directly from the company, and the empty packet could be a result of a mistake by the canteen staff. The burden of proof rests on you to demonstrate that the company knowingly supplied a defective product.