Ansal Housing - Flat booking refund

We booked *bhk apartment with Ansal housing (Ansal Heights Sec ** Gurgaon) in **** with total cost of Rs. **,**,***. We paid booking amout Rs. *,**,***. as per agreed plan at the time of booking, they were supposed to send demand letter of *% of total cost in every * months till **% of the cost and then rest on possession.
First demand letter was issued in June **** but they added a portion of payment (**k approx.) due in May and charged interest. they also added full fire fighting change (***% due) in *st demand letter. They mentioned service tax different at the time of booking and changed something else in demand letter.
we attempted to get clarity on demand letter, but they refused. We requested the latest ledger and noticed **% was due near completion and not at the time of possession. with all these irregularities, we spoke to their GM (Ranjita Krishna) and decided to go for cancellation in June **** itself. it has been * yers since we are following up. initially, they said they refund in Oct ****