...but I'm fairly confident this a wheel bearing sort of noise - it gets louder as you drive faster.
I came up against something similar at my forfour's MOT last November. There was a front lower suspension bush needed replacing, but it was only available as part of a complete lower arm unit which cost about three hundred and ten quid for the part. Doesn't leave a lot of room for manoeuvre.
Hmm, this ‘genuine’ ‘non genuine’ stuff is a debatable. By genuine one might insert ‘from MB dealer’? But MB don’t make suspension arms, they buy them in. They might use some kind of quality control which a ‘non OEM’ one doesn’t have. Then they put their markup on it!