It sounds to me like you need a specialist, not just a LR place but an out and out suspension and alignment specialist. Welwyn isn't *that* far from Chesham, Bucks. Look up a guy called Tony at Wheels In Motion. He is a god with such things.

Don't be too scathing of Polyurethane bushes though, as long as they're not the rock hard ones I have found them to be very good for certain things, especially ones which are hard to replace. Polybush do a blue series (comfort) and so do other companies - not sure if they are all available for the FFRR though.

You need to be methodical with this and Tony is exactly that. What you have so far is people who are treating the symptom, not the cause. If the bushes are shot then there must be a cause. Your nuclear option won't necessarily fix that cause - replacing a load of components is guesswork. I get that it is frustrating but you could easily spend a grand or two just to find the same thing happens again in 5k miles time.

What would I check?
All bushes, front and rear.
All drop links
All ball joints
ARB mounts and bushes
Geometry - 4 wheel alignment. All of it including the thrust angle. If it's driving one way and coasting the other due to the thrust angle being wrong it places a huge strain on steering components.
Shocks. Places like Kwik Fit can test these on a bumpy road simulator thingy.
Ride height - all 4 wheels. If out of spec then the geometry is out of spec, mostly the camber angles. That will ruin lower arm bushes quite quickly.

Like I said, Tony at WIM knows all about this. Worth talking to.

At £300 I presume she must have had a new egr valve fitted
it's around £30 to £40 to delete the egr with the new kit, I'd blank the vacuum pipe for starters.
has anyone recommended checking any of the rear suspension, as I have read on here so many times, peeps think that it is coming from the front, when in fact it is the rear.
I also see you haven't mentioned the anti roll bar links, these can be easily seen when you move the wheel on lock to lock, there is also a washer on the top fitting, I don't know which side it's supposed to go on, but I'm sure pete, haylands on here said it has to be fitted a curtain way, or it causes a knock.
I have fitted a set of britpart upper arms on mine, and so far they have done approx 20k, with no issues, I was fully expecting them to fail before now, they don't have a very good reputation.
As above advice, there is definitely something amiss, although I find it hard to believe that it's the same item over snd over.
hope hou get it sorted for your sis.
greg

The washer should be fitted on the "inside" of the drop link ie. on the opposite side from the nut, which is a bit counter intuitive. John
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mzplcg
Thanks for the suggestion that she contacts Tony at Wheels In Motion. I'll pass it on and see what she has to say. Maybe she will listen to me this time! Probably going to cost me money tho'.

Got no problem with people fitting poly-bushes to a properly set up and working system for good and specific reasons where its going to perform better than the stock set-up for them. The bodge is when they shove them in to cover-up a different fault. Personally I'm a "leave it stock unless you really know what you are doing" guy figuring that the factory engineers are pretty good at what they do and that most "could do better" issues are accountant driven where they try to get the price down from best of everything to what folk can afford.

greg
Inclined to agree that it ought to be a new EGR valve for that money, not the proper blanking job. But she has a history of bouncing between latest and greatest, newest cut price guru who promptly charges too much for too little. Spent far, far too much on her vehicles over the years and had more than one wrecked at her expense.

I agree that being the same thing over and over sounds unlikely but an L322 is way outside my comfort zone so don't want to get too involved. Free spannering for the nuclear option of doing everything I can handle but not diagnosis.

Thanks for the help.

Clive