Airtel Postpaid Plan — billing plan

i ve taken the airtel group connection plan five month back, my monthly bill comes arount 750rs, when i ve taken the plan company took the security of Rs 500 but my couligues had paid only 250Rs more over in my plan my std charges are 1.25Rs/min whereas others are paying 1Rs/Min for Std charges.
Moreover company has insured me that my 500Rs security they ll refund me by first two bills, but its not happened.
kindly change my std charges from 1.25/min to 1rs/min.

do the needful

thanks