The fraudsters pretend to be members of your bank. They use fake emails, text messages or phone calls with fake telephone numbers (spoofing) to give the impression that they come from the bank. By making alarming claims (including unauthorized transactions), the fraudsters try to panic those affected.
Variant 1: In one variant, the fraudsters ask for your PIN for your EC or credit card. After you have given your PIN, an unknown person pretending to be an employee of your bank collects your EC or credit card for verification purposes.
Variant 2: In the other variant, the fraudsters explain that they need a TAN (transaction number) in order to stop and reverse the unauthorized transaction. Everything has to happen very quickly. You should provide a TAN immediately.