This is almost clear now,He got his new connection on 15-03-08, so ,[ if the plan is H250, then he would have got around 560 MB free for 17 days in march, If the usage is jsut 1 GB,then,for remaining 440MB (@0.9/MB) he shud be charged 416/-, but it is not]becoz the plan is H500C, for 15 days it would be 250 rental and 754MB free day usage data. exceeded 1Gb, not exactly known, if it was 1116MB, then excess 362 MB(@ 0.8/MB ) sums up to Rs 290 .500 installation might be for a new telephone connection.I could not calculate for serrvice tax.waiting for shamvil to clarify.