Places that put you on hold, play music and constantly interrupt it by stopping the music and saying "Thank you for holding. A representative will be with you shortly" or the like. It always makes me think I'm finally going to get a human being. Once, it happened six times, so by the time an actual human answered I almost tuned it out.
Worse is if there is no music, thus the voice makes you think you have a person...but nope!