Firstly a sale agreement entered on 29.10.2008 is now barred by limitation. Next the sale agreement is not a registered document with proper stamp duty unpaid, hence it is not admissible in evidence. Even if this considered as a receipt of the money received, the claim for return of money is also barred by limitation. Further the clause in agreement clearly restricts the buyer from claiming the amount owing to his non-performance of the contract within the time stipulated in the unregistered sale agreement. Thus, the buyer stands losing the claim in all aspects. However, if you are willing to return the advance amount, you may decide about it, but be assured that he has no rights to forbid you from proceeding with the sale of the property to a third party, if he indulges in any such act, a criminal complaint may be lodged against him for illegal extortion and threats of dire consequences hereon. If the buyer is not coming for negotiations but is putting obstruction to selling the same to a third party, you may initiate legal action against him for his continuous threats.