The whole open door policy is a lie! If you make a mistake and bring up an issue with your manager you can bet that nothing will be solved. Not only that - they will retaliate against you. Suddenly you are the one with behavior problem and it's an official part of your review.
Basically you are stuck with two instead of one original issue. Not sure about other departments, but at Customer Service this is how it is.
Management is not your friend trust me on this!