I book directly with SS in the US and have had several cruise consultants over the years. When I first starting booking, the SS consultant would give me OBC, either automatically or if I asked about it at booking as an incentive. Most recently, however, I've been told that, since SS now has included excursions in every port, they do not offer OBC any more as it is not necessary to enhance the experience. That said, I would still inquire about it if the voyage was pricey already, since OBC comes out of the agent's commission.