Contractor not finised the work even after one year

Hi Advocate , I am Nandha Kumar from Coimbatore , Tamilnadu. Last year about in Oct 2014 my father started constructing the front portion of the house by demolishing the existing portion. After the RCC roofing is done it was left for curing & the Engineer didnt turn on to start the remaining work. Upon several calls he came & was arguing, that argument went on to quarrel & misunderstanding happened between my father & the Engineer. Now the house is left as it & we are following him for the last one year & no response from him. We went to his house & checked, every time he will say next week will start the work like that but will not start. Regarding payment we have made almost full payment only Rs.60000 left as per agreement. He never picks the phone & cuts the call. I am working in Bangalore & my father is in Coimbatore & he is almost 68 years old. The Engineer has taken the video of the quarrel happened between my father & the engineer & he is threatening my father, My father is afraid due to age factor & also they are staying alone. In this case please advise what should we do. Regards, Nandha Kumar