Sale agreement

Sir, I am purchasing flat in Bangalore from owner's share. owner owes money to builder and also he gives a flat to me 4 lakhs lower than builder as he needs some money. we gave 24 lakhs and when we asked he tells registration date cannot be disclosed . he also tells i am genuine since I have not withdrawn the chwque. but he was worried about the cash 12 lakhs we paid. He told i will not any money less than 12 lakhs. sale agreement is expiring this june 1st. his assistant said maximum we will try for registration in august at max. we can save some money if we receive CC and no dues certificate from builder(owner owes some money to Builder ) i feel, owner will cancel the agreement as the flats is easily going for more than 80 lakhs now) please guide me what is the next step i should take. 1. when will builder gives CC and NOC(immediately after construction ?). now only pending work is sanitation work and electricity and giving water connectivity). is this situation is genuine. 2 Who will come for registration(builder or owner) 3. what if owner stiil not sharing the approximate registration atleast. 4for agreement we made for our reference made betwen me and ownwer has that clause 12 + 12 cheque and cash on 200 rs franking. 5. what are the other options available in case to return the money back and cancel. 6. till today he has not withdrawn the cash through cheque and he claims genuine. 7. Should builder delay giving CC and NOC. please advise as my BP is raised since last week due to this issue. :( I am scared that I will get back the money given to owner. thanks in advance. Regards Partha