When visiting full-service restaurants in some places (this seems very common in the US, for example), the server brings a check at the end of the meal detailing the amount owed for food and drink and tax. When paying with a credit card, the customer gives the credit card to the server, who takes it to the back room and swipes it through the computer, printing out additional receipt paper showing that total paid, with blank lines for the tip and total. The server returns the card to the customer with these additional receipts and a pen; the customer writes the tip and/or total and leaves. The server then enters this information into the computer before the final amount to charge the card is complete.
Sometimes, the server enters a higher amount for tip/total than what the customer wrote. The customer can notice this if they (a) write the same amount on their own copy of the slip, (b) take that copy with them and keep it until the credit card statement is available, and (c) compare it to the credit card statement. On occasions where I've noticed this, the written tip was 18-20% of the [pre-tax] subtotal and the charged tip less than a few dollars higher.
From an individual perspective, the amount is often low enough that the time required to look up the credit card company's number, call in, jump through the voice menus and authenticate a couple times (e.g. via the automated system and then again with a representative), file the dispute, scan and send the customer's copy of the receipt (which doesn't necessarily prove what they wrote on the restaurant's copy), and do the requisite follow-up, isn't necessarily worth the value of the difference. The barrier to reporting is lower with some credit cards than others, and generally getting better as websites improve, but can still be relatively high.
From a server's perspective, a dollar or few from each customer can add up to a nice little bump in pay, with very little risk of negative consequences because even in the highly unlikely case a customer does notice, it's even less likely they'll also do anything about it and even if they do, the restaurant usually just gives up the small difference for that particular transaction without having to admit any wrongdoing. (If the difference is low enough, the credit card company won't even pass on the report to the merchant, because they don't want to put resources into following up). So the incentives appear to be well aligned for servers to add a small amount to each tip.
Other than always and only paying in cash, which has its own downsides, what's the customer's best response to this? Have there been examples where customers reporting such issues to the credit card company actually turned out to be the best outcome (e.g. earned the reporter more than minimum wage for the time spent and/or was effective in protecting a much larger set of customers)?
