Grand Circle Cruise Line

My parents are in Lisbon. They boarded the Corinthian for "Spain's Northern Coast and the Bay of Biscay" cruise. All unpacked. They were called to what they thought would be the muster drill, but instead were told the cruise was cancelled. Another poster (H20tstr) wrote me that they were supposed to be on the Corinthian last week, but their cruise was cancelled.

I assume that this must have been a mechanical problem. What kind of compensation did Grand Circle provide? We have cruised and traveled with them many times and have found them to be honorable.

No explanation provided (it MUST have been mechanical). Compensation was notable: full refund plus first class tickets home.