Brittany Ferries complaint: Noisy cabin

On 13th September we sailed on the night ferry Mont Saint-Michel. Our cabin was we think 7002 – booking ref: GL55663.
We needed a good sleep to drive down south to the Montpellier area next day.
When ferry left the port the cabin became noisy but we had experienced this before and previously the noise from the engines had subsided when the vessel was out on the open sea, so we went to bed.
The rattling and thudding of the engines became worse and worse, but we didn’t want to leave our bunks to complain in the middle of the night.
I did not sleep at all. My husband slept very little.
Next day, approaching passport control we looked back at the ferry and could see our cabin window directly above what looked like an engine room.
I was too tired to drive. My husband drove some of the way and we stopped in an aire and tried to sleep. Driving while tired is dangerous and against the law. I therefore believe we are entitled to a complete refund. If directed to a cabin in similar position on one of your ferries we will not accept it.