Yes, you should definitely call. You may have to get special approval and even pay a small fee to make the change, depending on how you booked. Most likely, you paid extra, though not double for your solo booking. If they permit the change, which I would imagine they will, you would likely pay the difference, which should be less than a full fare, depending on your booking. I recently requested a ship and date change, which is a little different, and I had to get special approval. Long phone hold, but well worth it.