Change in building plan without consent

We have booked a flat in society which is being re-developed. The construction was stopped for about 2 years and now as per new DCR 1991 amendment, the society was given permission to restart construction. I had paid the initial 20% amount as per the chargeable area ( super built up). Now the builder has changed the plan without our consent which has resulted in the increase in the carpet area. Also location of the flat which was agreed to us has changed.Now the builder is asking us to pay additional money since the carpet area has increased. The builder has cited the following reasons for the same - 1. Change in DCR 1991 and ministry of environment and forest regulations.2. Regulation for providing recreation ground as per supreme court ruling. We would now like to know why should we pay for additional carpet as we have already paid as per super built up ( chargeable area). Since the location of the flat has changed without our consent, should we ask builder to compensate us appropriately?