Call them, have all the order and shipping information on hand. IMO it will be a little awkward at this point seeing you were refusing delivery on something you ordered (imagine doing that with a pizza lol).
However I guess technically they should be able to work with you. It might be a little more troublesome because its not going through their normal return channels. Thats why I'd call asap so when it shows up there might be someone that has half and idea whats going on.