Fraudulent claim by land broker.

I wanted to sell my plot lands through broker, and the broker promised to sell all the plots for a total sum of 60 lakhs in a period of 6 months. The contract said that the property owner will sell the property to the broker or the person pointed by the broker for a consideration of 60 lakhs. I signed the contract without thinking much. The contract is unregistered and does not have witnesses. The actual setup we had was, the broker would find someone, and call me during the date of registration, and he'll take the price difference he negotiated to the buying party and the price he negotiated with me as his commission, and he'll pay me my amount and I'll register the particular plot in the buying party's name, the broker made me sign behind the contract I mentioned earlier, each time a plot was registered and I recieved money, he would indicate the amount recieved behind the contract and made me sign, again I didn't think much of it. Only the amount recieved was mentioned beside the sign and not the plot number or anything else regarding the particular sale on the day. I recieved about 25 lakhs from him and continued selling land through him for about 2 years without renewing the contract as it didn't really make much sense for our setup, but I continued signing the amount I recieved each time. I cut ties with him after he sold a plot without my permission and some else fenced my land. Now almost after 10 years from the initial contract, I got DTCP approval and trying to sell my plots, and now the broker shows up and claims that he has given me 25 lakhs and I never registered the plots to him for that money. Does he have a legal basis? How do I deal with him?