There is a fine line between not following instructions and being combative. The reason yours doesn’t work is because it opens the conversation up more for the employer to ask questions. It tows the line of being combative and telling the employer to pound sand.

There is no harm in telling the employer you’ll try to fix something. You just can’t commit because they’ll hold you to the standard you set. Committing to “do your best” can’t be challenged and most middle managers will think they won the conversation.