That does sound very expensive, I had a new Haldex pump fitted for less than that, I think the unit was £180 and they charged me an hours work which was something like £55, maybe with mine it was easier because they already had the whole diff out, I’d certainly get another quote, that sounds like a quote to replace it, have you got a stoney car park near you, a big pub or garden centre, might be easiest for you, find a quiet stoney car park and pull away really sharply, you’ll get the fault message if your front wheels slip a bit, it doesn’t take a lot, and as probably mentioned before you can still drive it ok with a failed Haldex it just won’t be 4WD