Plusnet (UK ISP) using reversible encryption, pasting passwords to users
blog.timje.info
blog.timje.info
You could get promoted to support level two somehow. You could talk to them in person. You could have someone else do the hacking. Does the UK have a civil liberties union?
EDIT: you might be able to get someone they do business with to fine them for not following best security practices. But hacking seems ethical compared to that :)