Non-payment of salary on termination of job

Hello, My father who was in the top management of a textile company had left his service recently. However, inspite of passage of couple of months, the employers are not paying the salary dues for last two months of service. What action can be taken by him? Also, since they have not paid the dues, we have not returned them the company's car. We have no interest in the car. We are just holding onto it to get the salary. Can there be any legal repercussions due to this action by us? We are sure that if we'll return the car, they would definitely not pay the outstanding sum. Please advice me. Thanks.