The Mestri has asking us huge amount of money

We have agreed to the Mestri regarding the renovation work and construction of an another floor. Initially we he said that it will take around 20lakhs and then my father asked him to bring an agreement so that we can sign that but he didn't bring that agreement but we paid me as he asked for the works in instalments but after a month we have a doubt about his work because the work wasn't standard as it should be so I asked him for estimation and he said 30laks we git shocked and then I have been asking him tor the estimation and he is been avoiding me for 3 months then I take I stopped giving him money and asked him to give me the bills and details for that then only I will pay the remaining amount or else I won't pay them. At that time I have paid him almost 12lakhs. He said that he added an extra 1lakh so that I have to pay that extra I said bring the exact details then I will pay. He brought me a rough estimate on a paper which is not even effective and he added the charges of the labour as he wish. And while I ask him for the number of the labour I will speak in front of you how can he take such huge amount. Then he refusing to give me the numbers and he refusing to show me the bills of the work. He says no one ever asked me for bills. I said stop the constitution works I will choose another Mestri to complete the work. Now what should I do if I want to take an action against him.