From their FAQ: If you wish to close your account you simply need to contact us via telephone or by the registered email address on your Betfair account requesting the account to be closed. We will then process the closure and confirm this to you.. So: info@betfair.com it is, or in Australia/New Zealand: ausinfo@betfair.com.
For people wishing to call, see: http://www.betfair.com/aboutUs/Contact.Us/
URLS:
http://www.betfair.com/
http://www.betfair.com/aboutUs/Contact.Us/
Please note that AccountKiller.com is not associated with the business listed on this page. AccountKiller provides easy-to-understand instructions and guides on how to cancel charges and relationships from the list of businesses on our site, we have no affiliation with these businesses.
I’m closing my Account as from today Oct 19th