issue of my mobile no. to somebody else

Location/place: indore

Name of company/service: airtel

sir,

i m madhur jaiswal from indore, i have been using an airtel number (98935-65656)from past 5 years, on 1st october 2009 i came to pune so i was not using the number. i was in pune for one month so dindnt use the number. when came back to indore i found that my sim was not working so i called there customer support and there they told me that sim is working and when i tried my calling my number someother person picked the phone and till that time the number was issued to me.The person in customer service of airtel told me that the number is in my name in their database. after that they issued the number to that person on postpaid and was transferred from my name. i want my number back since it has been 4 months and its causing me trouble not having my number which i have been using since last 5 years…kindly help me in getting my number back