Legal heir certificate

Hi sir There was a property of us in hyd purchase in 1980 Which was purchased by my grandmother an she has been expired in 2007 an that property holder became my father an he is also expired in 2013 An that holds to me an my mother an we wanted too sold the property and we sold it with the help of advocate without legal heir certificate he make possible an registration has done in 2016 an we has applied for legal heir certificate which we not get till now an some of amount has been stopped by purchaser fr that legal heir certificate an now after the registration the owner of property is saying that we have 2 pay the amount on government value of rs 7% which is cost rs 50000 for that legal heir certificate so I want 2 know that is legal heir certificate wanted 2 owner after the registration has happen an y an who should pay that amount 2 get legal heir certificate an the advocate is from the purchaser side so please suggest me what 2 do Thanking you sir