Contact seller first, take pictures, and open the box.
I once had a box with excellent seals, but was way too light. To be on safe side, I called customer service. After cutting seals, it was full with empty Lego bags, the booklet, some cables for weight, and 1 little bag of old Lego (to make the Lego sound when shaking the box). Customer service told me to throw it away and shipped a new box. That's some service!