The last three or four times I've withdrawn money it's been in my account the same day, usually in the late afternoon if I do it before lunch.

I can't see the ACCC ever allowing them to charge for a quicker transfer here. If they can do it faster then the ACCC would probably say that's what they should be doing anyway, without charging for it.  I could be wrong but I'd be VERY surprised if they could get away with it in Australia.