Swaping from one unit to other unit

We have booked a flat in one property 1. During booking, builder(sales) told we can swap from one property 1 to other property 2 under same builder anytime before registration and that amount can be moved to swapped flat. We swapped to other property on that basis. While booking we asked about car parking area & location(since it is flood prone area) and sales person promised it will be on stilt. Sales guy told swapping is just a simple procedure and he can take care of that. During agreement time, we asked them to give confirmation on writing since location of parking is not mentioned in the agreement. We got reply from CRM stating that it will be on basement. We got shocked and asked CRM and sales team about it and now they are refusing to allot in the stilt floor, so we informed through mail that if the parking is not in the stilt floor we would like to cancel. Builder is threatening us like we have opted for loan and you will lose money because of cancellation. Now builder is also telling how did you booked apartment without cancelling that property1 agreement. Property 1 flat is converted as model house and builder is telling you have to opt for other apartment in property 1. My question is when builder is telling without cancelling the agreement legally, how can I swap to other property, how can builder convert the apartment allotted to us as model house. Is it legally allowed. We have paid money towards Property 2 also. They are not refunding our money. Please advice