i dont have airtel but what appears from OPs post is that he used it for 1 month (or Ndays) and used 26MB only.But so, if say, on one single day you used 26MB and didnt download for full month, airtel wud charge u rent of 399Rs plus 23MB extra that he downloaded in one daySo thats cheating. Because as normal user u wud assume that 399Rs/100MB scheme means u can download total 100MB per month.