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?