SBI Credit Card — shoppmart epay kerala----- fraud on the behalf of sbi card.

Address: 400614

I have sbi credit card, i received a call from number [protected]
From master and visa verification department at sbi on 02-sep-2017. He (Executive) told me that sbi card shutdown the rewards point from next month, and will issue a new discount card micro chip card on behalf of this cards. And say it is compulsory for all, and this one time card charge is rs.7000. So first bank debit the charge of rs. 7000.
But he assured that it will be adjusted through discount vouchers and the same amount will be received with this card. I was hesitating to provide otp but somehow i given otp. Immediately my account got debited with rs.7799 is spent on shoppmart_epaykerala. I immediately realized something fraud happened and i reacted quickly to reach sbi. I given the whole scene to them and got my card blocked.
The transaction is yet to be claimed by the merchant.
They sbi told me that i would raise complaint when the after investigating that transaction is claimed for settlement. I wonder how they (Frauds) get my details. Please guide me what should i do further?