Well, I got my X5 back from dealer and although it took them an extra half day to sort out the rattles, I am happy to say NO MORE RATTLES!

If anyone from Calgary is reading this, Andrew, the tech in service at BMW Gallery, sorted it out.

He had to adjust rear seats where they latch (cheers Jamesboags), and also put thin foam tape between the plastic flap and the other plastic on the rear half door.

I drove around today and heard nothing. I will keep you updated if the rattles return.