You can get a 25% refund on the ticket price for the part of your trip that was affected refunded if you're delayed for at least:
one hour for a journey of up to four hours
two hours for a journey of between four and eight hours
three hours for a journey of between eight and 24 hours
six hours for a journey of more than 24 hours
If the delay time doubles, then you should get 50% refunded.
For cancelled ferry trips, you should be offered either an alternative sailing or a refund on the ticket price.
If you don't get a response from the ferry company or they can't to resolve your complaint, you can contact ABTA, the official complaint handling body.
Read more on how to claim for ferry cancellations or delays.