Bharat Sanchar Nigam Limited [BSNL] — Non refund of security deposit after surrendering lanline/broadband

Address:	641038
Website:	BSNL

I have surrendered my lanline/broad band[protected] at coimbatore saibaba colony exchange and submitted relevant papers at customer care centre attached to gm's office coimbatore on 30/10/2015. Though
I was informed that refund cheque will come within 3 months, i have not got the refund even after 6 months. There is no change of address.
I wonder in these days of technology adoption, how this much delay can happen. Does it show bsnl simply do not bother about the public they deal with. May i have solution for my problem soon ?