dissel

i have a question on bsnl BroadBandConnection i have 2 accounts(one with my dad and another for me).we both use rs.250 plan(it allows 400 mb free download, no free night surfing)my dad uses only upto 100 - 150 mb p.m.but i sometime use 500 - 600 mb p.m.so it costs more on my telephone bill.so...