Airtel — sim connection not change from postpaid to prepaid, airtel office told change not done before 120 days

Address:

Asha apartments 50/1 itakgachha kol-79, Kolkata, West Bengal, 700079

Dear sir/madam,
I (Lalit kumar prasad) holding ph no [protected] with postpaid connection for last 01 yr and 06 month approximately, with add on no [protected] for 02 month. When i visit to airtel office they refuse to change postpaid sim which is add on no not change into prepaid view sim not completeld 120 days
Where as bill came more as told by airtel office since sim taken.

Therefore request you to kindly review my issue as soon as possible from unnecessary bill amount.

Thank you