Dust is a part of life here in Oz....
Heck your door seals to do this get some graphite powder and sprinkle on the rubber door seal this should then transfer to the door jamb/body of the vehicle and be visible where there is a gap that is where the dust is coming into the vehicle just my 2 bobs worth .....
Heck your door seals to do this get some graphite powder and sprinkle on the rubber door seal this should then transfer to the door jamb/body of the vehicle and be visible where there is a gap that is where the dust is coming into the vehicle just my 2 bobs worth .....