Refund money after Cancellation

I wanted to buy a Flat with a reputed builder in Bangalore. I had paid the builder 10% of the amount (10 Lakhs) and got the legal documents. On verifying the legal documents with advocate , I got to know that some of the legal documents related to land ownership were missing. I did many follow-ups with Builder and did not get any good response. I finally decided to cancel the deal. Builder is now refunding only half the amount(5 lakhs) as he says the payment schedules are time based and they will 18% of the amount withstanding from the start of the construction. this is pure cheating the customers and at the time of booking, I understand it is written in the booking application form. Please note that I have not signed any agreements - Construction agreement or sale agreement yet with the builder. I planned to put a consumer court case against the builder as I have sent 2 legal notices. My question is that the value of the Flat is more than 1 crore, so should this case go to National Commission or will it go to State commission. My fear is that if it goes to National Consumer Commission in New Delhi, it is very difficult for me to fight this case instead of getting it done in Bangalore.