Such an interesting thread...
OP saw an item that belonged to someone else, but didn't return it back to the appropriate place (which would have taken seconds to do so), and now has been charged for said item.
It just seems that when it's someone else's money, people aren't careful, but when it's their own money, watch out!
Only so many options, as have already been discussed, as to where the pillow is. At this time though,
DCL is looking for replacement value of the pillow, so it is up to OP to work that out with them.
I agree that it would be very helpful for DCL to have an inventory list in the room, but really, is that necessary? I am renting a room for a week, so everything that I find in the room when I check in, except consumables such as: tissue, soap, lotion and brochures, should be in the room when I check out. No inventory list needed as I know that the throw pillows, artwork, furniture and electronics don't belong to me, and so for the week my family and I are there, we take very good care of these items, and we sure as heck make sure they are all there when we leave the room.
Hope OP gets this straightened out, Tiger