I recently made a large purchase and the retailer made a math error and wrote down the wrong final price on my invoice/receipt (the top price was correct, but when they added in the taxes they screwed it up so that the final price I owed was too low by $1000). I paid by credit card and was charged the lower price.

A week or so later, without talking to me they charged my credit card $1000 in a separate transaction. I was a bit surprised by this because I didn't sign for the higher amount, give them my card, nor authorize the second transaction.

Ethically, it's fine that they got what I verbally agreed to, but did they break the law? I don't think I will pursue it, but could I in principle force them to return that $1000 based on the fact that I did not agree to pay it nor sign for it?

  • 2
    Since there's a receipt showing the higher price, they'd probably any suit.
    – RonJohn
    Dec 15, 2017 at 17:34

2 Answers 2


They didn't break a criminal law unless a DA could prove beyond a reasonable doubt malice aforethought to deceive you, which would be impossible given the facts you present.

Whether they broke a civil law is decided by a judge. The judge's gavel defines the law. This presumes you go to the lengths to get this in front of a judge, not a simple thing and usually resolved in private settlement, which means no ruling is ever made. The standard of proof is ”51% more likely than not", but again, given your facts I consider it highly improbable that you would prevail in law.

They didn't break Visa/MC's terms of service. In fact the credit card companies provided the mechanism by which this adjustment was made: he would be unable to run a totally new charge, as he would lack your physical card, or your CVV2 which they are not allowed to store. If they did store that info, then they violated Visa/MC's rules bigtime, oh dear yes - the rules are PCI-DSS.

  • Expiry may be stored as long as (at least) PAN is strongly encrypted or otherwise rendered 'unreadable', although merchants are encouraged not to store any CHD if it is not 'necessary'. CVV2 is 'sensitive authentication data' and may not be stored after auth. See DSS page 8 under 'PCI DSS Applicability Information'. Anyway it is possible to do a transaction without either expiry or CVV2, it just usually costs more which is why merchants usually don't want to, see security.stackexchange.com/questions/21168/… Dec 17, 2017 at 8:49

If it was an obvious math error that is recognizable on the receipt, you owe him the real price. The mechanism for him to get it of little relevance. At best, you would have the right to step back from the sale.

If you think you will be able to convince a court that you really thought the lower price was the original price, you might win. It is not enough to claim you missed the math error.

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