I was not supposed to be charged by a specific merchant
If you don't recognize a charge, don't worry. Just search for it in your Transaction list. If it's a mistake, freeze your card and contact the merchant for a refund. If they don't give you one, you can raise a chargeback dispute. Check how to do it here.
If you have a police report, please provide it.
If your card is lost or stolen, report it right away.