Airtel — charging for aadhar linking to sim card

Address: Mumbai City, Maharashtra, 400053

Dear sir/madam
Recently, i visited an airtel simcard retailer for getting my sim card connected with my aadhar number. But he asked me for rs.30/-. I told him that him that it is a free of cost service then he retorted that for that you have to go to airtel store where it will take two hours to get the process done. I very well know that for prepaid customers, retailers can do the linking. Please look into the matter. There people are doing open loot in broad daylight and tarnishing the brand name of airtel whose i am a proud customer.