Facing problem in plot registration due to middle man

Hello sir, I am purchasing a plot 30x40 for amount 12,70,000 rupees from a land owner via a broker, I have paid 70,000 as advanced amount(this agreement is on plain paper) The broker has prior agreement (stamp paper)with owner to sell the same land with another person for rupees 10,00,000 and the other person has paid 2,50,000 to owner as advance Owner do not know that the broker is selling it for 12.7lakh to me we(broker, other party and me) have agreed mutually to trash the agreement when I pay 2.5 Lal to other party after registration on my name But the owner of the plot is not ready to proceed registration with me. He says his lawyer has said to register only with the first party with whom he has agreement of 10lakh And the broker and other party do not have money to pay, so they are asking me to pay amount 7.5lakh to the other party to register on his name from owner. And later he will register on my name The govt value of land comes to 10.8Lakh I have already paid the registration charges which 72000 to the broker and I have the challan of 70k on my name which is expiring in 7days or else I have to cancel the challan which cost me 10% of stamp amount I have few questions here Is there something wrong if I go ahead with the seal? Should I stop and get back my challan and advance amount ? What is the legal advise to purchase now ? We asked broker to cancel the deal but he says he does not have money Please advise