Bharat Sanchar Nigam [BSNL] — surrender of bsnl land line [protected]

Above land line was was surrendered / asked to cancel through letter dated 27 jan 20 submitted to bsnl ranni - mundapuzha customer care office on 30 jan. But still sending bills every month fo payment and refund not paid. Complained online also on 11 feb. Ref. Krl/co/2020/3824 but no reply or action taken for redressal.

Require immediate withdrawal all bills issued, permanent disconnection / termination of the line and refund the security deposit.