Booking amount taken for a unit that was already sold, No BBA signed as yet.

I had booked a flat under M3M Natura on my wife's name with Mrs Monica Garg by paying booking amount of Rs.50000 via card swipe on 22/09/2019 Within an hour I found that the layout shown by M3M sales guy was different than what was shown to us. This unit had a size of 1192sqft. On contacting, I was assured that they will work out a solution After another week of discussion and providing some bad alternative units I was explained that the unit you are booking is much better. Somewhere in last week of Sep 2019/ initial week of Oct 2019, I was given a unit option in Sierra68, which is a different building but under same project. I was promised that the layout shown to me at time of booking is being sold and asked for more payment. Then I made another payment of 50000 rs via card swipe and 1 lakh rupees PDC for 10th October. The unit now blocked was S3-705 under Sierra68. For this unit I was asked to agree on payment of 10 sqft extra as this unit had a size of 1202 sqft. On 6th October I again visited the property to show it to my father and found that the unit has incorrect layout and I am being sold the same layout that was available under Natura. For this I raised objection and asked for either clarification of issue or cancellation of my booking with refund of my amount. By this time I had already given another post dated cheque of rs 200000 to be paid on 20th Oct 2019. On 7th October 2019, I again went to Sales office and was taken to site to show the exact layout, now I was offered a unit S2-705 under Sierra68 of M3M On agreeing to this layout and for the extra charge of 10 sqft, I accepted S2-705 unit and my PDC of 100000 rs was cleared After another week of not hearing anything from the builder/ sales team, I enquired and found that there is some issue and this unit is still under the cancellation process and hence cannot be booked. Now as of today I am under distress as I have paid 200000 Rs to M3M, with no assurance on what flat I am being promised and have another payment pending on 20th Oct 2019 for another 200000Rs I have sent written email complaint to M3M Sales guy and his colleagues that either provide me a solution or cancel my booking and provide refund. To this sales guy mentioned if you want to cancel, please go ahead but we will not refund anything. I want to get out of this trouble, please provide guidance, I do not want to loose my hard earned money on which I have paid all taxes to the government. All payments were done online and no cash was invloved. I have marked a stop payment of my cheque dated 20th Oct 2019 and also informing the M3M sales team. As per recent conversation, they are providing alternate solutions but also threatning to forfeit my booking amount.