Airtel — my airtel prepaid number issued to someone else

Address:

Hyderabad, Andhra Pradesh

I have been using airtel's prepaid number *598 for the last 5 years. For the last 5 months i was not using this number since i had to travel frequently out of country, but i made it sure that the sim is in working position. After some days sim didnt work, it displayed "sim card registration failed". I thought that my sim card must have become faulty since i had not used it for months. So i call to airtel's customer care to get a duplicate sim card. There airtel's representative told me your no status is active and says me' go to the nearest airtel office and give your id there and we will issue new sim card for the same your old number. That the number has been disconnected and has been installed on some new sim card, hence i cannot get this number back. Today my sim number is issue for other person. The reason they gave me is that "you've not received any incoming or outgoing call in the last 3 months, so it got disconnected". I 've this number on my visiting cards/i card/atm/irctc web site and lots. More than 1000people/clients have this number. I feel completely devastated. I need this number back at any cost. How can airtel disconnect this connection without any notice? Even if i was not using this sim card they do have our e-mail id, residential address, alternate number. Cant they even sent one notification? I feel really cheated. How can i get my number back? Please help