I would imagine that most people have the same goal when going grocery shopping: go in, get what you need, and get out as soon as possible. We may be busy unloading our carts while the groceries are being scanned or bagging things as they are finished. One thing I have found very useful is to carefully watch as your groceries are being scanned to make sure you are charged the correct price.
Yesterday, I went to the store with my husband. He kindly put the groceries on the belt while I stood and watched the screen to see each price as the groceries were scanned. We were only buying six items, so I didn't expect to have any trouble, but I would have ended up paying about 25 percent more than I was supposed to for the same items if I hadn't carefully watched and caught the mistake. The clerk insisted that I was the one in error, and that the advertised sale price was for a personal size watermelon instead of the one I got. I invited him to go back and look in the produce department and see the sign carefully marking the watermelons on sale and also told him where to find it in their weekly ad. After a few minutes of him going back to where the watermelons were, he still tried to convince us that it was for the personal watermelons. Because they offer a price accuracy or the item is free, my husband asked if this was a situation that would apply. Some stores offer the price accuracy so you will have confidence in their prices, but you have to ask specifically or they will not offer it to you when they make a mistake. Usually we don't take them up on their free offer if they make a mistake, but because of the behavior of their clerk, we did. He did end up apologizing for taking so long after the transaction was completed. It reminded me once again of the importance of watching carefully to make sure you are charged the correct price.
I have also seen errors that would have been in my favor, but have brought it to the attention of the clerk as well and had them charge me the correct price even though it was more then I was originally charged. If I expect the store to be fair with me, I also expect to be fair with them.
I am surprised at how often I am charged the incorrect price. Whether it is groceries or back to school items,
What can you do? When writing my grocery list, I write down the price I expect to pay for each item. An even better way would be to write down the actual price next to the item on your list while you are shopping. Either way, it will save you from having to go to the customer service lane after your transaction is completed.