Contract Modification by Tacit Acceptance Despite Express Written Consent Clause

A party contesting a judgment asserted that the trial court erred by upholding a contract's validity based on an implied consent to the modification of the agreed-upon compensation, arguing that such modification required an express written agreement as stipulated in the original contract. The Court of Cassation rejected this appeal, reasoning that while the contract mandated written agreement for modification, the party's consistent and unequivocal performance under the new terms, without timely objection, constituted a tacit acceptance of the revised compensation, thereby validating the modification despite the absence of a formal written amendment.