See Ist of all, u hve should go through the RTI Act in totality including the rules maid thereunder including that of fees rules passed.
The information asked by u must not be costing that huge an amt. of Rs.21000/- as u quoted. Still, the act prescribes that before providing any information which would cost to the public authority, it has to give a explanation as to the calculations arrived. That means, in the reply to ur application, the institute must have given u a step by step calculation as to how the amt. of Rs.21000/- hve been arrived. secondly if at all the inforamtion costing them dear enough, request them to provide it to u in a CD which the act prescribes to be not more than Rs.50/- per CD. and in case the infor. supplied is after 30 days, then even that amt. is exempt.
AS a whole, i don't think the kind of info. asked by u costed them dear enough and perhaps, they r not looking in a mood to disclose them and hence discouraging u.
And i tell u their is no problem at all. Go to the senior offiicer in rank in the INformation section, their and file an appeal to him within 30 days sharply explaning that u r not satisfied with the reply of the institute.
And after that the final appeal shall lie to the CIC within 90 days of the decision of the senior rank officer.
So go to the institute website and find the person senior in rank of the PIO in info. section and update abt. advancements of ur case.!!!!!!!!!!
& here is the link below containing the list of the DEsignated APIO's, CPIO's and appellate authorities. AS per ur problem, u can to the the appelate authorities.
https://www.icai.org/post.html?post_id=4741