Vodafone India — settlement of my vodafone bill

Address:

New Delhi, Delhi, 110059

My name is aakash bhardwaj, my e-mail address is [protected]@gmail.com.
I was using postpaid number of vodafone i. E [protected]
I was using plan of rs:-399 per month, later i changed the plan to 299. The sum of bill should be 1097, but when i saw the bill it was 1987.
I asked the customer care agent that how is it possible. He explained me which i did'nt understood later the conclusion was wavinng out 27/- rs from my total bill. And when i have not paid my two months bill my connection was disconwnected then how they added third month bill.