Airtel Prepaid SIM
Cell No alloted to someone else

I was using Airtel Friends card since 5-6years. Now since 2-3 Months I was not using it since I was out of state (Maharastra). Now I came back the sim was unable to register on the network. When i called the CC they told me that no is allote dto someone else. My no have still validity upto 2014. I am going to launch consumer care compliant. What else i should do before that?

my No-9970277155