Have you tried any local motor factors? When we had a Fiat (from new) we had a 'rattle' over bumpy roads, and it sounded like something under the dash (certainly nothing major). I said to Mrs M that if we told the main stealer they would probably have the dash out and create 3 more rattles! so we lived with this minor irritation. When it came to its first MOT it turned out the ARB links had a little movement, so I sourced a pair off Ebay and fitted them in 40 minutes (nuts a little rusty). 'Our' little rattle disappeared! So maybe OE parts not so good? Scroll forward 11 month to next MOT and the rubber boots on the new ARB links had opened up like petals! So I went to local factor and got ones made by 'First Line' which the guy said had a 12 month warranty so may last 1 month longer
New ones fitted in 30 minutes (copperslip from year before
)
Give credit where it's due, I sent a photo of the 'petal' ones to the Ebay vendor, who offered to send more, but I told him I had to get others on the day to get MOT, so could he send 50% refund - which he did. I think Ebay ones were £14, factor ones £22, so roughly 50% more, but they were good 3 years later when we sold the car.
ETA when I did some searching First Line say they are uk based and great (well no company would say they were bad), promoted like a 'new age' QH supplier. I guess the parts may come from wherever, but if their quality control is good? Factor man said they were good (but again he wouldn't say otherwise) - At least I could return them easily if I had a problem.