
I really sympathise with you as have been in that position myself. We had booked a cruise a couple of years ago and had to cancel a week before we were due to go due to OH's health problems. He has no travel insurance for his condition as the insurance companies won't insure him for anything less than a premium of £900 per week

so we took a chance and booked a cruise that left from England (he is not allowed to fly) as he had been in remission for two years. Unfortunately his health problems then escalated and we had to cancel thus losing the money we had paid.
It was really disappointing but nothing we could do about it - we took a chance and it didn't come off - so just had to swallow hard, choke a bit and mutter various swear words under our breath :D Now I drive to France as there is some health care available under reciprocal agreements and can get back fairly quickly if the need arises.
Hopefully you will be able to get your money back soon and be able to book something else :)
Looking on the bright side the sea would probably have been so rough that you would have been ill all the way there and back and would have thought it a lot of money to have paid in order to have spent your whole time studying the inside of the toilet :D