Same issue here. For the B pillar, adding insulation to the seatbelt adjustment part fixed the issue. For the door, mine was the window switch. Adding insulation inside the window switch made it better but not 100% fixed.

The upper b pillar garnish is prone to rattles in many vehicles. The times we have this issue it’s related to the the felt on the adjuster gone missing, either from installation or from supplier. The second is there is a spring that retains tension on the adjustment button goes missing, the button will still appear to have the spring but that’s from the mechanical adjuster that it sets on, the garnish has one as well. The third is the felt along the sliding portion of the garnish, the whole part that slides up and down, has its felt missing. The last thing it can be it the actual mechanical adjuster, behind the garnish,that the seatbelt is attached to has worn, it has some plastic bits to it, some grease along the sliding portion will help that out. Hope this helps, it takes a bit of investigation and trial and error to find and resolve. The door handle is likely an over extension issue, which it actually has to be replaced to resolve, the retention of the plastic is gone, usually caused by too hard of a pull and or the flicking (grabbing, pulling it out, and letting it go) of the handle. A little diy remedy can fix it, just again, trial and error.