Airtel — whatsmob activated without my consent

Whatsmob service activated without i asking for or activating from my airtel number. Amount of rs. 75/- is also deducted from my prepaid balance. I deactivated as per sms from airtel. But money is not credited back in my prepaid balance. I got message that this service is activated n my airtel mobile number. I even do not know what is this service. I never activated it. This is really a theft by this company airtel. I request you to look into this & get my hard earned money back from this thief.