Hi guys, thought I’d add to this. I found that I was getting a knocking noise from what I was suspecting was the rear passenger C pillar but couldn’t pin point it. The rattle/knocking was present on any road that wasn’t baby smooth, and was really starting to wind me up… anyway, after trying many things including plugging in the seatbelts, taking out the parcel shelf and even punching the c pillar a few times in the hope the problem might disappear I finally found the culprit… Upon moving the rear seats slightly forward from their fully back position on the sliding rails the sound is gone! I’m on 60k and no other sounds so seems I have a quiet one luckily (touch wood)! I hope that this helps other people solve the issue before assuming the worst like I did!!!