Airtel — sim card & aadhaar linking

Address:

Kohima, Nagaland, 797001

Sir/mam,
Some airtel offices in kohima are charging rs. 50 - 200 for aadhaar linking. This is a daylight robbery. Since i know that its suppose to be free of cost, so i went to link my aadhaar card but and i refused to pay i was told that the line is down. It seems the line is up only for those people that pays money. I mean, how can i pay for something that is free of charge? Please suggest some ways to tackle this situation.
Thank you.