Real estate broker want commission without any legal documents like legal forum or any agrement

I am a buyer of a flat which registry is done on 19th feb 2014, After that a broker continues call me any try threatening me this broker shows me this house initially but did not tell me or sign any document about the percentage term & conditions and after the deal was cancel from my side because of many reasons like (high price of the property , 10 lakh advance without knowing the seller or this random agent) and many more reasons, the deal was cancel earlier. After some time i get in touch with seller directly because this flat is near by 200 meters from my office & this time i regularly checked many properties directly and also i am seeing the ad of many property, i also see the add of this same property in ghar dekho.com & property wala.com after that i deal with the seller and the seller is in urgent need of money so the seller agrees me on 35 lakh (earlier dealer tells me 42-45 lakh) after that we decided to registry the flat. After that the property agent comes to know about the registry and they continuously harassing me that u are now liable to pay 2 percent of the property value. How can i pay the 2 percent to her and how can she asked me to pay that without any sign documents or agreements from me.