My husband and I are on the Mombasa to Bombay sailing after yours and I know how upset I would be if ports we were scheduled to visit were changed, however, hopefully I can help to make you feel better. We were on the Royal Princess last summer in the Mediterranean and visited both Santorini and Kusadasi (for the second time). You MUST go to Ephesus when in Kusadasi. We went again on our second visit as we found it so fascinating. Santorini is by far the most beautiful and interesting Greek island we have visited and I know you will enjoy it. Just wander around there and enjoy. Great shopping also. Stop and have a drink at one of the cafes on the side of the cliff, overlooking the harbour - magic!
Have a great cruise.