Airtel Prepaid Deactivated

I have purchased a Airtel prepaid connection for business purpose, since there is a delay in opening the business i have not made outgoing/ incoming calls. Last month my connection was deactivated without any intimation and when contacted Customer care they said that the connection was disconnected due to no incoming/outgoing calls for 90days, they also informed me that the number is allocated and activated to another Customer. I was in continuous touch with them for the past one month but I haven't got the number back. can i proceed legally?