For this reason alone, Betfair has no reason to ban or close your account when you should win. This is what Betfair first became famous for; peer-to-peer betting. Whilst the Exchange account won't be closed for winning, there is an additional commission rate.
Fast Funds is the quickest way to make a withdrawal, and get your funds from your Betfair wallet to your bank account. Fast Funds is currently available to customers in the UK, Ireland and Spain with a Visa Debit or Prepaid card. The withdrawal must be made to this Visa card.
