SBI credit card FRAUD Danger- SBI not willing to investigate.

My Mom recieved a call from some one marketing airtel money. This person gave details starting from her DOB, Address and mobile no. Further they told her that the Airtel money would be enabled so that she can purchase anything in selected locations. The amount swiped was 10k in two transactions. They asked her to give the OTP, and things were fine for 2 days Post this she was not able to use Airtel Money, since practically it was not charged. She called up Airtel and they declined any such transactions We did put a complaint with SBI and blocked the card. SBI Bank doesnt seem to own SBI cards hence didnt get much support there. Also the customer care was arrogant to make things worse. They didn't take responsibility to investigate further and give details where the money was transactions. They say that its fraudulent calls coming from hackers who has all our details. This hacking is common across country, and nobody knows how to tackle them. SBI wants us to bear the cost since we gave the OTP. Is there any way we can fight against this? Not sure if these hackers are We put a complaint in the local police station against SBI Card not investigating it and proving the truth, but of no use. Now we are not sure how to proceed on this!!