If you're experiencing water seepage from the flat above and the owner or association isn't helping, you have several legal avenues. You can start by issuing a formal legal notice to the neighbour. If that doesn't resolve the issue, consider approaching the local civic body, filing a suit in civil court for mandatory injunction, or lodging a complaint with the Dy./Jt. Registrar of Cooperative housing societies. You can also complain to the SDM for abatement of nuisance.