you definitively need to avoid this hotel despite a good location on La Rochelle harbour.
I needed to cancel my reservation more than one month in advance, durintg the touristic season, the manager refused to refund me.
It simply means they sold twice the room, there is absoluttly no problem to rent the room in June in La Rochelle.
Of course they will argue it was mentionned in the sales conditions, however, I already had several times similar issues (for business purpose), I always been refunded, some times paying small penalties.
I think they simply forgot what an hotel should be : service, service and ONLY service.
Don't go to this place!!