THEY made the mistake - THEY need to ship your Items.
I like Plush Puppy but have heard they're pretty hard to deal with. They normally have very fast shipping

in this case...they need to fix their mistake and you shouldn't have to return a thing if your original order went to someone else unless they send you prepaid postage....but you need your original items first.
They're running their business pretty rinkydink - I know they make a ton of money - their stuff is good - but expensive