Standard Bank Transfers take between 1 & 5 days to reach your Betfair account (deposits) or your bank account (withdrawals). After your first Instant Bank Transfer (which can take up to 90 minutes), subsequent deposits & withdrawals are immediate.
For most successful Fast Funds withdrawals, winnings will be in your bank account in seconds but this can take up 2 hours. On some rare occasions, your bank may not be able to process the payment and withdrawals can be unsuccessful. This is nothing to worry about and it is recommended that you try again later.