If you suspect an unauthorised transaction has been made on your account, check if you made any other purchases on the same day before contacting your bank. The item could have been mistakenly billed under a different name. Also, ask anyone who uses the card with your permission (such as your partner) if they made the purchase. Once you have confirmed that the transaction was unauthorised, contact your credit card issuer immediately. Credit card issuers provide 24/7 customer service to address these matters, so do not hesitate to take immediate action. Failure to do so could make you liable for the unauthorised transactions charged to your credit card.