The first thing to do is to stay calm, irrespective of the size of the charge. Take a few minutes to analyze the billing and scour your memory; don’t put it off, because sometimes immediate action is absolutely required, but don’t get so upset that you act before you think.
In most cases, you will be able to eliminate a mistake made by you as a possibility relatively quickly; usually thinking about the charge for a few quiet minutes and/or talking to whoever might be authorized to use the card (remember, most any family member can use the card online with or without your permission) will settle the question.
If the mistake was yours, grin and bear it and pay the bill; if not, it is very important that you determine whether or not actual fraud was perpetrated by a third-party. There are some easy indicia of that. For example, any charge for a tiny amount such as one dollar, often tells you that someone was “testing” the efficacy of their fraud before actually spending a significant amount of your money.
Unless you can absolutely eliminate fraud by a third-party, you need to assume that it was just that, report it immediately to your credit card company and take whatever other steps are necessary to protect yourself. This of course would include examination of every one of your credit card and bank accounts. Best to take no chances; when in doubt, cancel them out!
