Yes, I have stayed twice in hotels mostly occupied by a wedding party, and it is definitely something to be avoided at all cost.
If there had been comething really contestable about the cancellation of this reservation, the official authority to contact is the DGCCRF (Direction Générale de la Concurrence, de la Consommation et de la Répression des Fraudes) --
https://www.economie.gouv.fr/dgccrf