Bharat Sanchar Nigam [BSNL] — refund of security deposit for my bsnl postpaid number

Dear sir i have converted my bsnl post paid to prepaid on 16 february 2017 clearing all the dues regarding my post paid number. Sir after that i applied for refund of my security deposit on 16 april 2017 giving complete details of my bank account number. Sir till today amount has not been credited to my account. It has been approximately 6 months and i have visited the bsnl exchange several times and they tell one excuse after other. Kindly address my problem.
Subscriber name : adil ahmad sofi
Subscriber's mobile no : [protected]
Account no of my post paid number :[protected]
Circle : jammu & kashmir