Bank response to stopping ********** payments

Phoned Nedbank within minutes of abeing ****med over the phone by someone pretending to be from the bank to stop a payment to takealot. Apparently you cannot stop the transaction at any stage. Even though I phoned takealot to tell them not to send goods. They denied any knowledge of such a transaction with my details- card number or phone number . Useless giving a number with the notification if they can’t do anything.