EU Regulation No. 1177/2012 (pdf) protects the rights of passengers travelling by sea or inland waterway.
The Regulation provides that passengers affected by cancellations are entitled to either:
- An alternative sailing at the earliest opportunity, under comparable conditions and at no additional cost, or
- A full refund
You should contact your travel provider in the first instance. If you’re unhappy with their response, you can make a complaint to the National Transport Authority.