Regarding Billing information

Hi

Actually i am affect from airtel plan.Customer told like 399 plan unlimited to broardband connect without using landline but i m getting billed amount 2500 Rupees .Actually i m using per day half hour.how come billing like this.I cancelled airtel broard band connection but they generated next month bill also without using internet connection .
Still i have total amount 2500 rupees.

Good bye....