BSNL / Zte Ev - Do — Billing problem of ZTE EV-DO

SIR

I am ANIRUDDHA SINHA lives in Bolpur.I bought a BSNL ZTE EV-DO from bolpur BSNL office on 24.04.2009.(Reg no.202505).As I was told the monthly charge is Rs.500+ tax.But they have send me the bill amount of Rs.1572 for the month of april(for 7 days) and for the month of may(for 31 days).After long conversation with the SDO i had paid Rs746.Now again for the month of june they send me the bill of Rs.755 in stead of Rs.500+tax(10%).So I am requesting you to kindly look after this matter as early as possible.