Occupy a flat without getting poss. letter from builder?

Sir, I am a PSU employee, booked a flat at GUWAHATI, in august 2008. Builder had pursued me to take loan from LICHFL, from where he got the loan for the same project, a G+3, 6 flat provision. The loan was sanctioned immediately, where loan amount (Rs. 600000) was 1/4 of the proposed price(Rs 2600000) as per the agreement. Loan was sanctioned in April,2009. Maximum amount I paid from my pocket. Within 2 years builder had constructed the floors and walls, and drawn 90% of loan, only Rs. 60000 was left with LICHFL. He forced me to pay almost all the money. I paid approx Rs.1900000 to him. Only Rs.150000 I did not pay to him, which with his verbal agreement used for putting tiles on flat by other contractor as I was not satisfied with his raw work, where my expenditure was around 2.5 lakhs. He again and again forced me to pay the remaining amount. When I refused, he stopped the construction of my flat. On repeated request also he did not complete the construction. Instead he let the watchman stay in my half-done flat. He fetched Rs. 50000 extra for electricity connection, grill etc. from me. Electricity Connection is in my name and also I am paying property tax in my name. Other owner also faced the same problem. But somehow they they managed to complete the work themself and occupied the flat without waiting for possession letter from builder as he has refused to complete the work as they were local to Guwahati. As I am a non-local of Guwahati and after waiting for 5 years, experiencing mental trauma by investing all the money of my parents and mine, after getting no response for continuous request to builder, finally I decided to complete the work on February 2014. Watchman was thrown out with help of other flat owners. I hired another contractor to complete the work, who give the estimate of Rs. 8 Lakhs, which includes water proofing of walls(quality of brick was substandard, as non water-pipe carrier wall also soaks water), putty, painting, doors, window frames, aluminium windows, grills, electric wiring (which builder did is of too raw quality), bathroom accessories and some other civil works. I tell him to carry on, to somehow finish the work. But, to my surprise I find that the land document is not correct. The "DAAG" no. allotted to this plot is wrong. Then how do LICHFL give the loan to the builder as well as me? The manager when approached, to file a case against the builder said to do a out of court settlement, as civil cases takes very long time to settle. All the flat owner together send 7 reminders to the builder to complete the work (including common area) but there is no response. All the 5 flat owners has occupied the flat except me without possession letter, as builder is not responding to any of the letters. I feel really cheated. It seems that the dream to own a flat for a middle class person, who know nothing about the complex laws puts all the hard earn money to have that are to cheat! Lawyers, only knows money, Where they get money, they find the loopholes of laws, and goes behind that, as the builder and their association has hired so many of these lawyer "street dogs" to cheat people who serve for the wrong cause and therefore "servant" to those who pay a handsome amount to them, leaving aside morality. Is there any morality of lawyers? Or All of them only knows money? Can the law be not be modified or enact to save people from the cheating of builders as we do not have enough money to buy a plot of land in proper location. Can there be not a provision to punish those "law knowing" people who take advantage of the loopholes to harass general people! Sorry Sir, I became little emotional. I do like to request to please furnish me what to do regarding this case, which are as follows: 1. Is it right to occupy the flat after completing the work myself, which builder is suppose to do? 2. What action including legal can be taken against the builder? 3. What action including legal can be taken against the banker(i.e., lichfl)? 4. What action including legal can be taken against the lawyer who frame the agreement knowing all the facts and providing loyality, "servant-ship" and "morality" for wrong cause to wrong person? 5. What will be the Income Tax filling procedure, can I claim deduction under 80C for principle and section 24 for interest. Sir, I hope to get a reply, as the situation has emotionally and practically degraded me to continue my day to day work.