Réclamation pour produit défaillant

Dear [Mr or Mrs or Sirs], We have purchased [produit] from you on [date] and have the regret to inform you that until now, it has never functioned as expected. We remind you that we insisted on the point that it should [spécifications de fonctionnement] and that you ensured us of its compatibility with [produit]. We trust you are fully aware of the inconvenience this causes and that you will [action requise] with no delay. We thank you in anticipation for your willingness to put an end to this situation and look forward to hearing from you Yours sincerely [votre nom] [votre fonction]