Cancellation & Amendment fees are based on a number of factors but can be quite heavy depending on when they occur relative to the travel date. The closer to the travel date booked the higher the fees.
Cancellation fees were introduced because it was discovered that when unsure of desired travel dates, people would often hold space on 2 or 3 dates.
Because of the popularity of the ferries this often meant that a sailing would show sold out when in fact it might not be
If illness is the cause of a cancellation or amendment it is important to provide a doctors travel advice on official letterhead and often all but the credit card fees can be refunded