SAD REFUND AND DOCUMENTS

HI I AM PRATIK 

PLEASE INFORM ME DETAILS ABOUT SAD

WE ARE IMPORT CHEMICALS FROM CHINA AND SALE TO INDIAN LOCAL TRADERS IN GUJARAT AND ALSO SOME END USERS WE PAID VAT TO GUJARAT GOVERNMENT BY OURSLEF AND WE CANNOT FORWORD ANY CUSTOMS CREDITS LIKE CVD SAD OR CENVAT.

SO PLEASE ADVISE US IS IT POSSIBLE TO CLAIM REFUND IF YES WHICH DOCUMENTS REQURIED AND IF WE PROVIDE ORIGENOL DOCUMENTS TO CUSTOMS CAN WE GET BACK IT AFTER WE GET REFUND BECAUSE AS PER MY IDEA THEY ASKING FOR ORIGENOL DOCUMENTS. AND IF THEY CANNOT BACK US ORIGENOL DOCUMENTS WHICH PLACE WE NEED TO COMPLAIN .