Caller: Unknown credit card company

Received an automated message saying unknown charges were on a credit card. No statement of which credit card or which company was calling. All a bit suspicious. At the end of auto message I was given the option to either [1] accept charges [2] decline charges [3] listen to auto message again. When I pressed 3 to listen to message again it diverted me to a caller. The person on the other line answered hello how can I help you. I said you called me so how can I help you. He insisted that I called him which is very weird. He then hung up on me. I dont think a legitimate bank would do that. So who called? - scammers / timewasters / frausters etc etc etc