I used Centerline when I had my United interview and got the job offer. I know some will say don't use a prep because they give you canned answers. Centerline doesn't do that, what they do is get you use to speaking in public. They basically help you communicate what you are trying to get across. I think alot of us know what we want to say, but when we try and say it does not come out the way we waned it to. They don't change the person you are, they just polish up how you communicate it.