Brittany Ferries' flagship, the Pont-Aven, will be out of action for at least another week.
The Pont-Aven was towed out of Plymouth to be taken to France
The company said a date for the ferry's return could not be confirmed and no more bookings on services operated by it would be taken until 25 August.
The Pont-Aven developed a cooling fault last week in Plymouth which left her engine room deluged with water.
The £100m flagship was taken to Brest in France for repairs, but returned on Tuesday after generator problems.
Wednesday's 1300 BST crossing to Santander had to be cancelled and hundreds of holidaymakers were re-directed to other ports.
The Pont-Aven, which has only been in service for five months, was taken out of service at Millbay Docks on Tuesday after a cracked cooling valve let water into auxiliary engines.
A company spokesman said: "Brittany Ferries staff are continuing to make alternative travel arrangements for those passengers affected by the unserviceability of Pont-Aven."
The ship's licence to carry passengers has been revoked until the ship is repaired.
Once the Pont-Aven is back in working order, the Maritime and Coastguard Agency will inspect the ship to ensure that it is safe before re-issuing a licence.