Sorry you feel that way, but 3 days is totally usual for bank withdrawals in the UK. For example PokerStars takes 3-5 business days for withdrawals.
PokerStars take deposits by credit cards etc so obviously a completely different situation, Intersango say that they check several times a day for bank transfers - this implies that they also process withdrawals several times a day & these take under 2 hours to clear in the UK period, I can send them money & they receive it cleared to their bank account in under 2 hours & they can do the same - it's not exactly dificult & if they can't then they should let there customers know this, how long it will take & when it is finally done