Freight rates in the container shipping industry are quite volatile. They are published regularly based on certain indexes and make a daily rate bargaining impossible. Carriers as well as customers agree long term freight rates to achieve longer term planning security. However, customers have the market power to enforce a published rate if it is lower than the contracted rate. We report about an approach that supports the shipping company to determine contracted freight rates under the consideration of this ``unfair'' customer behavior using segmentation-based pricing methods from revenue management.