Transdeals.in — Credit card scam

I received credit card from indusind bank. But I didn't activated that card for 2 days, in between these two days I received calls from the fraudsters claiming that calling from the bank. They asked me that have you activated your card yet or not? I didn't responded them due to my work for 2 days. After 2dayd again I received call they asked same question. I thought only bank and me supposed to know that I didn't activated my card yet. So I proceed further as the fraudster said and activated the card. After activation he asked me service that is for free travel and discounts on holiday travel hotel bookings. I declined them that I don't want this service but still he was asking me for that. He was continuously telling me that you don't need to pay anything on this service and the next few min I seen that there was an outstanding on my card 16000Rs. My first point is how fraudsters get to know that my card is not yet activated?
I am sharing the number of the fraudsters below

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