Thanks for your replies. I think I may have been a little early in judging the car given we only picked it up on Wednesday!
Double checked the tyre pressures, filled it with V Power diesel and spent this morning in the car with coffee, glasses and the instruction manuals.
I have a clearer understanding of how things work now I think - Auto is really "Comfort" mode but there is some automatic adjustment made to ride height based on speed.
The manual seems to infer that Comfort should be soft - We live rurally on the Rutland & Leicestershire borders and are lucky enough to have some of the best driver's roads in Britain right here. So good in fact that most of the major car magazines and a certain television programme use them for road testing and shoots - Having read the manual and with the weight of a full tank of juice on board I put the car in "Dynamic" mode and set off on one of my favourite routes. I've driven that route since I was 17 years old in various different cars ranging from my first car, a rusty brown 1978 Scirocco GLS all the way through to the likes of a 997 GT3 so feel I know exactly where most of the surface's features are and how they change the way the car behaves.
In Dynamic....OH MY GOODNESS...It's a changed car. It hunkers down and eats corners in a way far greater cars couldn't manage. Reminds me a little of the Bentley Continental GT in its characteristics and the way it exits bends.
I'm not so convinced there's anything really wrong with the suspension anymore - Just needed to read the books and make use of the settings. I hope I'm right anyway! We'll see. There is another issue I've discovered but I'll post separately about that.

With regards the trailer, I'm handy enough to have replaced the original wooden floor with the manufacturer's spec composite upgrade last weekend, but I'm not getting involved in its mechanics. Girls and horses. I'd never hear the end of it if I didn't get it right first time.

I've given it to our local trailer repair firm who are taking it out on their car today to see if they can replicate the problem. They think they've isolated it to the brakes being poorly adjusted since the damper in the hitch at least appears operate properly.