Airtel India — sim card reactivation

Address:

602024

I used my number in postpaid for 6 months and then i changed to prepaid. My father forgot to pay the bill before he changed it to prepaid. After using it for 4 years, now i found that the number was taken out of service and i couldn't even get the number back in postpaid, after paying the bill and maintaining some minimum balance.

I need my old number back...