Disputed Amounts 28.1.1 If any portion of an amount due to a Party (the “Billing Party”) under this Agreement is subject to a bona fide dispute between the Parties, the Party billed (the “Non-Paying Party”) shall, prior to the Xxxx Due Date, give written notice to the Billing Party of the amounts it disputes (“Disputed Amounts”) and include in such written notice the specific details and reasons for disputing each item; provided, however, a failure to provide such notice by that date shall not preclude a Party from subsequently challenging billed charges provided that such charges were paid. The Non-Paying Party shall pay when due all undisputed amounts to the Billing Party. Notwithstanding the foregoing, except as provided in Section 28.2, a Party shall be entitled to dispute only those charges for which the Date was within the immediately preceding eighteen (18) months of the date on which the other Party received notice of such Disputed Amounts.