Airtel — Bill Generated after my airtel broadband disconnection

Address:

Matrusri nagar ,Hyderabad

I requested for my fixed landline/broadband disconnection on Dec06/2021 with a request no:[protected] and my Fiber ID[protected]_ap.
I moved to other broadband connection after requesting to airtel for disconnection by mail(attached for reference)and also by calling customer care multiple times.
But still this month by bill got generated and asking me to the bill(589rs),
Which is very disappointing, even after calling multiple times..CC executive and supervisor also spoke. Late they told backend team will call...still i will get so many unnecessary calls and asks for OTP for cancelling the connection. But still nothing happened, its Ridiculous, Very bad service, Lot of disturbance, unnecessary pressure, . Kindly do the necessary action and do the needful.