Credit card companies claim they investigate disputes, but in reality they can't afford to do much investigation over small amounts of money. In the US the rule is when in doubt go with the buyer, which means sometimes dealers get ripped off and some decide not to accept credit cards any more, but it's also a good reason for buyers to use a credit card to protect themselves from thieves. Seems in France the rule is when in doubt go with the seller and using a credit card doesn't give a buyer any protection.