I've been running into the same brick wall for a while, from both a developer's perspective and as a user. There's some big fallacies propagating amongst people who think they know what usability is. Now I'm not going to claim to be an expert, I know more then I did a few years ago when I first encountered the area as part of my formal studies and had a pretty contemptible view of it.

And that's the first trap: a little knowledge is dangerous. If you don't know enough to know how much you don't know, you're never going to be able to make progress.

So I'm on the phone to EDF Energy, I'm used to dealing with tired-sounding underpaid people who sound like they'd like to strangle you with the phone cable or having to keep taking the phone away from my ear to key in numbers. Not with EDF, they seem to be running a shiny voice recognition system. Either that or their phone droids are chowing the happy pills like there's no tomorrow and are very rigidly scripted. Either way it gets confused if you add please and thanks on the end of things. I guess that's not an input they're used to.