We have had 3 of these now, on our Egg card which is an online one - in Feb, autotrader.com, $30.00; in July, auto-by-tel service $29.95; and in Sept cars.com $50.00.
I have reported them all to Egg, the first has been credited back but the second hasn't yet and I only just told them about the latest one. I asked if Egg could find out how they got our card number and their only suggestion was to cancel the old card and get a new one, which takes 10 days and means you can't access old records any more, blah blah - surely they should be able to contact the trader and ask for details of the transaction?