We had a crap holiday in Chateau de fretay in Brittany. However when we asked for our money back on arrival, owner only agreed to 15% of first week, and a refund on second week if he could rent out accomm for 2nd week.
French Tourist Board told us we could INSIST on a full refund in facilities/accommodation are not what we were expecting. They were extremely helpful. So if anyone finds themselves in similar situation, you can demand full refund (whether you get it or not is another story..)