Airtel Postpaid Connection
Bill cycle change with out intimating

I have a post paid airtel connection from Karnataka circle (Bangalore - 9845450267). My billing cycle is 5th of every month. Yesterday I have received a bill for 20 days and when contacted the customer care, they have said that, Airtel needed this and so doing. When e-mailed to the customer care, the reply was to pay for the unbilled too and any discounts will be adjusted next billing cycle. There is no proper support or service from Airtel now a days and need to call atleast once in a week to airtel customer care to register complaints.