what actions can be taken when i purchsaed

A building on land contract, have put over 180,000 dollars in payments repairs and labor into the building (past the eqity postion)and i have an investor and business partner coming in and we were ready to pay it off per sellers and my agreed price and title company found that the seller had previously sold thats on land contract but warranted send my contract that there were no other land contracts or outstanding contracts on the property and signed and recorded that. How do we get the first land contract buyer to sign a release when she is refusing that has not been to the building and seven years or paid taxes in 7 years and what remedies do I have any charges that I can play against the seller for fraudulantly stating in my contract if there were no other contracts outstanding other than his mortgage that would be paid off at Closing