Brittany Ferries review: Charging for cancellation voyage

As property owners in France, ourselves and extended family have been using your services for the last twenty three years. On this occasion my wife booked the passage but cancelled it unclear as to whether I would be able to cope with the long drive on the French side following spinal surgery instead of postponing it following consultation next tuesday. I appreciate there is a charge but the whole £300 plus seems excessive considering we want to complete the journey ASAP. Many thanks S F Elvins