Trai — illegal transfer of my mobile number

Address:

560026

Airtel network provider has transferred my prepaid registered mobile number to unknown person without my permission and without my knowledge. Please let me know what procedure for make complaint against airtel network provider. I am using [protected] number from past 4 years. On 03/10/2017 airtel network provider has blocked my number and transper my prepaid registered mobile number to unknown person as postpaid connection. Regarding the issue i spoke with airtel customer care executive officer but they replied me they don't have documents for issue and not registered case with regard to mobile number change. Kindly advice me regarding issue to get my number return back.