I had this with Virgin Media (UK ISP). I called them and the support guy asked for my secret password. I assumed it was a security answer so I went through a couple of obvious ones like mother's maiden name. After a few attempts, he stopped me and said my password was strange because it was just a bunch or random characters. At this point I realised that not only was he expecting my actual account password for verification but it was available in plain text for him to manually verify!