False call transact money form active card with reference to Ola Money

Hello sir
Yesterday my mother became a victim of cyber crime on debit card. 
She recieved a fraudulent call from someone asking for her card credentials to keep her card active. 
Unfortunately she gave the debit card details including the otp and her account got debited by rs.9999 with reference to a transaction on ola money.

The transaction time was around 4:30 pm ist.

The phone number that she received the fraudulent call from is [protected].
Can you please block the transaction if its from the same number i mentioned?
Also would be highly appreciated if you could help me find a way to track this person.