Article 1223 of the French Civil Code
In the event of imperfect performance of the service, the creditor may, after formal notice and if he has not yet paid for all or part of the service, notify the debtor as soon as possible of his decision to reduce the price proportionately. The debtor’s acceptance of the creditor’s decision to reduce the price must be in writing. If the creditor has already paid, in the absence of an…