Self — airtel payment bank wallet

On 23rd of may last, following a fake call from airtel payment bank, i added an amount of 2001 to my airtel money wallet. Immediately after the amount was deducted in the head of airtel payment bank, resulting no balance in the wallet. How is it possible to leak money from wallet. Please help me. When i requested him money back he asked me to go through the official process they had and to add more money with a target of 5000. I followed him accordingly and completed 5000. Now the process is complete but the refund or otherwise the offer is pending.in order to get the offer, he is further asking to add another 1500. But i have no money to add. So, you are requested kindly to detect the hacker.