How can we get back our house?

we had a house, 3 years ago my mother decided to sale. someone brought it but he did not paid it in cash. he paid it by installment and there are time he gave us goods as payments, where is it is not the agreements... 8 mos. my mother decided to stop him to paid the house, and she decided to gave back the partial money of the buyer... the buyer refuse to get the money.. we don't have land title for the house because we paid it trough installment. the buyer paid the land with out asked permission on us. we want to file a case not only against the buyer bit also against the Local goverment officer who allow the buyer to pay for our lot.. what kind of case that we are going to file against them.. can we get back our house?