Essentially, the Court held that, when they orally agreed to vary a substantial part of their agreement, they also implicitly agreed that the “written amendment” clause no longer applied. If the first party has accepted it consistently, it can be implied that the new payment date is the middle of the month and not the first day of the month. In the whirlwind of activity, written agreements sometimes cannot keep up with business developments; and in the event of a dispute, the parties may find that their contracts do not say what they thought or do not reflect their actual practice. .