Airtel — airtel monthly bill over charges

Hi this is suresh, i am using airtel postpaid ([protected]) from last two years. I am facing a lot of issues in my monthly bills from last two months.in before last month's bill, they charged extra 500 rupees. And in last month bill they charged extra 336 rupees. I complained same thing in customer support call, but they didn't responded correctly. Due to this i am planning to change from airtel to other network.