Airtel — Deposit money not yet initiated

I took connection of airtel, dth and broadband, for dth connection the security deposit of 1500 was paid. i was told that if I have active connection for 12 months then this money will be refunded. but after completing around 12 months of connection I submitted my set top box in good connection but not they are telling since you were in airtel black your active connection and they are not refunding the amount.