The problem to be solved is why the person doesn't learn or change when they know about the mistake, not the mistake itself.
You might start by directly asking, "Why do you keep making this mistake?" It might be because they're careless, or lazy, or maybe they really don't believe it's a mistake (they just acknowledged the mistake to get you to go away). Or maybe they just need a little help, such as automated reminders to get them to check for those mistakes.
Sadly, there are people who will not learn from either kindness and teaching, or harshness and harrassment. In the workplace, you can make an appeal to the manager, but perhaps only after discussion with coworker has failed to produce the desired results.
You might start by directly asking, "Why do you keep making this mistake?" It might be because they're careless, or lazy, or maybe they really don't believe it's a mistake (they just acknowledged the mistake to get you to go away). Or maybe they just need a little help, such as automated reminders to get them to check for those mistakes.
Sadly, there are people who will not learn from either kindness and teaching, or harshness and harrassment. In the workplace, you can make an appeal to the manager, but perhaps only after discussion with coworker has failed to produce the desired results.