I have booked a flat in Srijan Centrum Block 2, 2...

I have booked a flat in Srijan Centrum Block 2, 2D and have paid the final installment. The lady, Shreya, the only person available has refused to give me a letter of possession or even say that the flat is paid off. They have not cleared the accounts and falsely charging me for Rs. 40,000 interest when we have ALWAYS paid on time of before time. They have not deducted the TDS AMOUTS that we have paid. They have failed to clear the accounts for the last one month. I am an NRI and want to stay in the flat when I come in a month. They are simply ignoring my local representative. I am very dissapointed that after paying the full amount, they are not cooperating and harassing me. I don't see why I can't move into a flat that i have already paid for. Can somebody who has authority please intervene and help me. I hope somebody notices this and has things ready by February 4th, 2020 before I take a more extreme step for this kind of fraud..
Shabana Akhter