Many lost their money in online frauds this year. The year saw more educated people being targeted than those who are not well educated. Most people lost money in frauds that did not require much skill to implement.
Most fraudsters use women to call up people to source their card details. Social engineering skills are used to elicit information from the card holder. Sometimes the callers call up to 'warn' about suspicious transactions for which card details are required.
Once information is divulged, more details are sourced using social engineering skills. Once the call ends, the customers can soon expect short messages from the banks. Nowadays even one-time passwords are being harvested by fraudsters from gullible customers.
Banks and credit card companies would never call for sourcing personal information from customers. Only a set of private information is asked to verify customers by banks. They will never ask for card number, CVV numbers, PIN numbers and so on. Therefore never share these numbers with anyone.
If you receive such calls, ensure that you talk tersely to the caller. Ask them why they need the number because it is available in their systems. In most cases, such calls will end there. The PIN and passwords are the private property of the user, it is not for sharing.