1) under terms of agreement signed by you with landowner after construction of building you were required to pay Rs 10 lakhs to the owner
2)you have duly handed over Rs 10 lakhs to land owner as per receipt received by you .
3)i presume payment was made by cheque
4) if landowner has failed to pay you Rs 17 lakhs for sale of 3rd floor flat you can refuse to hand over possession but the problem is in your sale agreement consideration mentioned is only Rs 7 lakhs
5) the land owner can argue that full payment has been made as per sale agreement .
6) if you fail to hand over possession landowner will file suit for specif performance of contract and seek delivery of possesion
7) dont transfer electricity meter in name of land owner .
8) till landowner makes full payment start staying in said flat .
9) let landowner move court for necessary reliefs