Cheated and Fraud

Dear Sir, We had invested in the flat at Navi Mumbai for Rs. 19 lakhs. The property was basically under re - development, that means the owner of the land entered to contract with the builder for construct building under 50:50 ratio. We paid Rs. 7.5 lakhs into it. The building completed 2 floors. Thereafter one day cidco came and broke the building. The builder was nil and he was asking for money to help him out to again construct the building. After that we paid Rs. 2 lakhs to him. So total we paid Rs. 7.5 lakhs. After some day the builders father died and he not turned up to the property. The land owner called him several times and also send messages to him, but he does not respond. So the land owner gave the property to other builder to construct. And so the builder started construction the building. We were not aware of this fact that the land owner has changed the builder. When we came to know, we approached our builder and asked for the money to return or do some settlement. As we need either money or flat we invested in. Our builder said, i have invested in the construction and I am Nil and dont have money to give. Landowner is not taking responsibility. He is saying that you have not given the money to me. Our builder said u may go for police complaint but I cant help and on the other hand, the other builder is on the verge of completing the building. Need your guidance as what action we need to do as we need to file the complaint against the land owner and the builder under what section.