Airtel — Charging higher than the plan cost

Address:	Airtel India Trichy
Website:	www.airtel.in

We are paying 999 unlimited internet connection, for this plan Airtel is supposed to provide 200 Mbps speed internet connection, but they are providing 40Mbps of speed only. When we called them before they sent technician and changed the new router but no change in speed, few days before we sent am email they have replied this:
we have already changed your bill plan from Airtel-UL-Zoom 999 Unlimited GB (40Mbps/1024Kbps) COMBO Plan to Airtel-UL-Xstream 999 Unlimited GB (200Mbps/1024Kbps) COMBO Plan (Subscription) with effect from[protected].

As per the website 40Mbps speed unlimited internet connection cost only 499/- plus tax
https://www.airtel.in/broadband/Trichy?icid=footer
Kindly look in to this issue and help us to get the amount they charged and get the proper plan, service and bill from Airtel