Expat Properties — failed commitment on buy back before possession and overcharge of installment amount

We invested for a plot in harmony 2 on 15 dec 14 located in village sindhudurg and were told that with the mopa airport opening the investment would more than double. We clearly set forth our expectations that we would exit before possession and the agent jason agreed that expat will take care of the sale. Its been more than 4 years now and there have been contacts in bahrain changing. The new person states that we cannot sell and have to wait for possession and is not in a position to support. Not sure, why would things change when our intention was clear from the beginning?. Also, there has been an overcharge on monthly installments as per the agreement and is totally a breach of the contract. I have to call up to ask and reconcile with the company accounts but there has been little or no response on my query. Also our calls are declined on most of the occasions.