How to deal with fraud committed by builder?

* Building has improper drainage/sewage system due to which sewage water getting is getting accumulated at our entrance. This is a big concern and builder is not correcting this (blaming governement agency) as this situation persist since last 2 years. He might not be having legitimate documents with government agency for gutter connection and the gov agency doesn't have any record of legal drainage connection of our building with external (gov) gutterline. This is confirmed via gov agency & builder doesnt have any such document whch gov agency is asking. Even in the surrounding area sewage water has accumulated. In short sewage system is not proper/legitimate hence the problem. * Builder does have BU permission but sewage system is not legitimate. * Also Builder is trying to give handover of our building and has left us on our own since last 6 months. We want to take handover but with solution of sewage system. (legitimate) How can we make builder solve our sewage problem?