Airtel — changing the broadband plan

Address:

West Bengal

My airtel broadband fix line number [protected]
My account number is14706424.

I was told that my airtel broadband plan will be changed from 1999 to 599 but it has been a month but my plan has not changed .
While calling airtel customer care i am being told that not to use airtel broadband connection but earlier the same thing happened i was told not to use the connection and i wont be charged but after six months the bill came along with the executive and i had to do a settlement and i had to pay 9000 rupees for not using the airtel broadband connection for six months. Same thing is happening again and i am being mislead by the airtel people for paying the unnecessary payment for again not using the airtel connection.
Please find some solution to end my problem.

Regards
Md. Kamran
Mobile number - +91-[protected]
Address - 13/1A, BRIGHT STREET, KOLKATA -700017