A hacker took over my partners e-mail and sent out requests for money to all addresses listed, saying an accident had occurred in London and they were in need of money to pay hotel and hospital. The secret code had been changed so my partner cannot use his computer. Is there no way to stop the hacker continuing sending mails? If you lose a credit card you can immediately contact the bank to stop the card being used, why isn´t there a similar method to stop hackers?

First of all, create a new email address and tell all your contacts about the situation, so that they can disregard/block email from your old email address. Then, if relevant, tell your ISP about it. Good luck.