Cheated by broker on property sale

Hi .. we need advice. One of my relative was doing real estate business. He approached that he had a seller who is willing to sell his land to us.. we agreed to it . We haven’t spoke to the owner of the land and never seen him in person, since he mentioned owner is out of station. Broker ( relative) was a mediator and we didn’t push him much for the detail as we believed him. We transferred 50% of the land value in advance to the broker account and he said he transferred to the owner in June. We made a agreement to register the land in sep however that document was not registered it was just a stamp paper signed by both the parties. There was delay and broker gave many excuses for not resigtering . Recently when we checked EC we found that land was already sold to some one else in sep . Broker is still claiming land was not sold and refusing to provide owner contact no and address please suggest how we can get our money back from the broker.