Airtel — money deducted online from my bank account but not recharged

Address:	New Delhi, Delhi
Website:	Airtel

I have recharged my phone from bank app on 13 december 2017
. I always do the same kind of recharges.
Never been in such situation.
Amount deducted rs 500 from bank but airtel did not recharge my phone balance. Now i have 5 rs as a talk time.
I am at loss of 500 rs. Without any reason. I can not call my bank for this cause no balance in phone. What should i do.
Where is my money gone?? Do any one have any idea??
Or should i get an idea?