Stop payment of cheque

Sir/madam,       I am Manmohan jha from bangalore.  I booked a flat with a builder costing 7.5 lacs and booking amount of 3lacs with option  1 lac imdtly and rest 2L within 25 days.  2 days after i paid 1Lac their representative came to my home to gv documents They gave me approval form, photo copies of deeds, MOU(not signed by MD or any one from builder and also on Rs 2 stamp paper saying that i wl get on 200/- stamp and sihned by MD too once  rest 2L is cleard).  Same time they offererd me if i pay rest 2L on same day they wl gv 5% discount on 2L and furniture coipon worth 2.5L, firstbi denied as my personal loan application was still in process.  Customer care ppl started calling me many times insisting to gv POST DATED CHEQUE OF 5 days advance by giving surity that they will not deposit in bank before asking me. I handed over the post dated cheque of 2L. after that i smelled something about froud of the builder(not sure), and the site doesng hav all clearance also to start construction.  I decided to cancel the booking (as per the unsigned MOU i am free to cancel any time and they wl issue PDC of same amt wth 120 days of processing period) so very next day i approached them to fill cancellation form and to get back uncleared 2L Cheque. They first tried to convince for other pmt options if amt is not wth me tht time.  But i said final to initiate cancel.  Then they said it is not psbl to cancl within 2days of booking so wait for one month it wl b automatically cancelled if second pmt is not made till the time.  And promised to returned uncleard cheque in next 2-3 days and gave assurance it not b deposited in bank.  I did stop pmt of the cheque on next day.  Neither they returned my 2L Cheque nor allowed me to fill cancellation form . my point is how safe i m in case of that 2L cheque fir which i hv done stop pmt from my branch.  Same time due to some reason my loan was rejected by bank so there is no sufficient fund in a/c.  These all happened bfr the date fr which i issued the cheque. Waiting for ur suggestion. Manmohan jha