Procedure for getting stamp duty and registration fee back in case of flat agreement cancellation

I have purchased a flat in one under construction society.lot of promises were made by sales person before purchase. A sale agreement was made on june, 30. Project is approved under RERA. Builder is now building flat as per details mentioned in brochure but all material being used is of poor quality. He is saving money especially at common areas like not using stone and scatting on walls of staircases. Providing CFL or bulb in common areas, doing painting but cheaper paint. Using fittings but cheaper one .not covering openings in common areas and so on....normally these things are no where mentioned in agreement. Is there any law against this to instruct builder to develop society properly. Few commitments are written in project brochure like commitment of Luxury, comfort, Safety and superior quality (as general) I have made around 70% payment and written mail to builder to correct such things . I also told him that I will not pay further if such things are not corrected. Suppose if builder or I cancel the deal. Will I get stamp duty and registration fee paid back... if yes, how and how much.