I'm not sure about the extra item charge thing, haven't come across that issue (yet....except when there is only 1 of the item available, then it disappears cos there's no additional items to buy), but I'd been noticing some sellers were saying their categories on listings had returned while mine hadn't... After a post on Facebook from another seller, I decided to try creating a couple of new listings (which I hadn't done for a while) and mine came back as well, but it didn't work for someone else, so I guess it's more a matter of try it and cross your fingers, I suppose. 
