Excess Price charges & less area given by Jaypee group

I am also one of victim of Jaypee group. I applied for 2 bhk in Garden Isles in Feb 2011. it is not even half the way of construction. On completion of 42 months I approached Jaypee for refund. They had refused me refund. or they said it will be refunded over a year. As I book the flat under subvention scheme. So, I had to pay 90%. From 24th month onward I had to refund the bank's installments also. I told them if they had don't money to refund they should give me a ready to move flat in Kosmo/Klassic or some other flat who price is equivalent to that. they said we don't have. You won't believe they harnessed me for around 6 months. They were not responding, At the end they offered me 1 bhk flat in Pavallion Court whose cost was 57 lacs measuring 936 sq.m as compared to 1250 sq.m project in Garden Isles. Moreover still not given possession. Forced me go for Registry for which I had to pay another 3.50 lacs. I want to take legal action for overpricing. Market cost is not even 45 lacs. How should I proceed ?