Airtel — deactivated my currently using number n given to another person

Address: Hassan, Karnataka, 573202

This is raju... I have been using airtel number from last few years... Few days back it has been deactivated and same number has been given to someone in somewhere else. I have used same number in bank account/ transaction... Without our permission how could they deactivate the number which has been using...
At any cost i need the same airtel number...