[mothered]

in places it says that the receiver can claim if the item arrives damaged. It doesn't mention anything (or from what I can see) about a parcel arriving without its contents.

Just because It doesn't mention missing Items on receipt, It doesn't mean they won't compensate for such Items.

They may well have purposely excluded that- just to minimize the number of claims for goods that never arrived. Of all SE's I've performed, seldom have I come across a company that (upon "seemingly" solidifying my claim that the package was tampered with In transit), rejected It altogether.

The item weighs next to nothing so this isn't an issue, it is making the envelope look like it has been tampered with, because they can't accept them if they have been ripped

Do they actually state that they don't accept damaged packages?