or better change to cheapest voice plan (200)like me with trib aa broadband plan.
line would be automatically disconnected after 2nd bill of 200+200+tax. security you paid would be 1000Rs.
Next time if you ever apply for connection(i don't gonna happen with pvt operators development) , plainly tell mtnl account officers mtnl owes you money instead, security deposit minus the last few bills. worked for me last time when security deposit was 3000 and now 1000 security deposit and again not paid.