You should talk to whoever you made your booking with. This section is for questions to be answered by fellow cruisers.
Surely you must have realised that tours involve road ransport; that is almost certainly going to involve a coach. My wife and I have limited mobility and we are aware of potential problems,. While I sympathise with you and your incapacity, I do feel that you have been a little naive. We are big fans of Fred Olsen Cruises, and I am sure they will go out of their way to help best they can if you explain that you have dealt with the poor travel agent. It is worth dealing with Olsen direct. You can always book with their discount then transfer your booking to a reputable travel agent to collect more discount. Best wishes. I hope you resolve this problem.