Builder not refunding money paid

Hi, My family has an old house in Vizag, AP. We gave it for a builder to demolish it and develop into group housing. As per the agreement, the builder is to build 5 portions and we are to split the portions evenly. According to the agreement the builder is to only build the property and we were to procure the electricity connections on our own or he can help to procure it and deal with AP Transco. My mother is not in a position to go around electricity department so she paid the builder to get the electric connections for us (we paid the builder after construction is complete). Initially the builder said we need regular connections since it is only 5 portions. After 6 months and we repeatedly calling the builder's office we were told that AP transco said we need transformer and so we paid more money. In total 1.5 lakhs were paid just for electric connections for 2.5 portions (builder owns the rest of 2.5). After 6 more months and struggling to reach the builder, suddenly they came and installed 5 meters in regular connections and conveyed to us that they completed their responsibility. We inquired and found that a meter installation costs around Rs. 5k including department fees + "extras". And now the builder says he had to pay so many electricity department folks to get the connections to the tune of 1lakh. We don't know how to get our money back, whom should we approach and what are options. Please advise.