Bharat Sanchar Nigam [BSNL] — surrender of landline non refund of deposit

Address:

Mysore, Karnataka, 570023

I was a loyal bsnl customer holding a landline since 1987 till 2017. Due to very poor service, with great reluctance i had no other alternative but to take the decision of parting my ways with bsnl after 3 decades and finally on 25.5.2017 surrendered my land line bearing no.2361827 at the office of the divisional engineer, telecom, south, mysore located at rttc building, tonachikoppal, mysore. I also surrendered the instrument as per their direction to the telephone exchange at srirampura on the same date and got an acknowledgement.
Before surrender of the telephone connection, i had cleared all my dues upto date and i was told that in my account i had a deposit of rs.1, 800 or so which will be directly transferred to my bank account. Asked about how much time it may take, i was told that it may take about 3 months. I was surprised to find in this age of electronic communication where anybody in any corner of the globe can be contacted in lightening speed, the bsnl being the communication giant needs 3 months time to verify and refund the amount that is legitimately due to me.
However, i have waited patiently for 3 months, but there is no information so far, nor a courtesy updating the status of my case.