Vodafone India — extravagant bill amount

The mobile phone connection (Vodafone network) is given by dist. Authority (Govt. Of west bengal) & maximum reimbursable amount is rs.400/- per month. Unfortunately, i used to receive the bills with absurd amount with very few exceptions till august, 2018 and after my complaint over mobile to customer care, the amount reduced to 234.80/- from the very next month. Surprisingly i have received 11 bills for 11 different months of same amount rs. 553.42/-. Is it quite realistic? As a result of that i had to pay an additional amount of rs. 3074/-.
My average bill is around rs.235/-, but i used to receive the bills worth around rs.550/- for a long time before my objection over phone. I also like to mention that the actual claim amount should be much higher than the claimed amount rs.3074/- as i only claimed the amount exceeded rs.400/- per month which i had to pay.
I sent three successive letters to the vodafone authority to work out the purpose & this is unfortunate that no action has been taken from a reputed company like vodafone.