Just saw that there were additions to this post, and as a result, actually read the post properly. I assume it is the the same with IF, and I used to have a Halifax account as well, so I always noticed similarities.
Basically, there never has been an immediate payment facility on accounts. In the old days, you made a payment on a certain day, which left your account by the end of the day, but this was not transferred to the payee there and then as it went through the normal BACS system which took a few working days. Halifax is not a clearing bank, so theoretically could take a little longer.
BACS is free, but my new IF option also gives me the option of paying for a faster transfer.
The simple answer is do what I do - you know when they want the money so transfer it so they will get it by then, not on that day.