Airtel — charging customers for postpaid bills even after they have raised disconnection request

Why should customer pay the bill for the company's delayed process? Or they should inform when they give connection. Make sure your customer service is proper. It is really sad that every company is doing this. Please give us proper explanation regarding this. I didn't use net for more than 1.5 month's. But i have paid 2500rs. And i have to pay some more amount until they finish the process. They said it will take 6 days to disconnect. That is their problem. Why should i pay for that???