Yes, I know, you can always challenge a charge, IF you notice it sneak onto your card A friend of mine has a system for that, at least at gas stations. Wheneve

Yes, I know, you can always challenge a charge, IF you notice it sneak onto your card A friend of mine has a system for that, at least at gas stations. Whenever he fills up, he tops it off such that the price ends in a 7. Then he scans his American Express statement for any gas station charges not ending in 7. Over the years, he's done several successful charge-backs.