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Detecting this kind of fraud is basically about big data analytics and anomaly detection. That's just a fancy way of saying it's kind of like finding a needle in a stack of needles! It's complex and expensive. Luckily(?) credit card companies have lots of money! They have to figure out what might be fraud so they can appropriately allow or block transactions. If they allow too much then there can be a lot of fraud. If they block too much then there can be unhappy customers.
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If I did speak to someone they would first have asked me to identify myself. However, they called me. I don't actually know who they are! This whole event could have been a scam to collect personal information from me. Had someone connected with me that way, I would not have given them any identifying information. They called me... at my registered (with them) phone number. They already know who I am. They need to positively identify themselves to me!