(5) The submitted parts mark-up or labor rate shall each be presumed to be reasonable, and shall go into effect forty-five (45) days after the manufacturer's receipt of its submission, unless, within such period, the manufacturer rebuts that presumption, by reasonably substantiating that such submission is materially incomplete, materially inaccurate or is materially unreasonable and providing a full explanation of any and all reasons that such submitted mark-up or rate is materially incomplete, materially inaccurate or materially unreasonable, evidence validating each such reason, a copy of all calculations used by it demonstrating any material inaccuracy, and a proposed adjusted mark-up or rate provided that the dealers submission is materially accurate, based upon the qualified repair orders submitted by the dealer. In such event, the manufacturer may not submit more than one (1) such rebuttal to the dealer, and may not thereafter add to, expand, supplement, or otherwise modify any element thereof, including, but not limited to, its grounds for contesting such parts mark-up or labor rate. If a manufacturer determines from any set of repair orders submitted under this section that the labor rate or parts mark-up calculated under this section is substantially higher or lower than the rate currently on record with the manufacturer for labor and/or parts, the manufacturer may, in accordance with this subsection, request additional repair orders for a period of either sixty (60) days prior to or sixty (60) days subsequent to the time period for which the repair orders were submitted for purposes of an alteration, and shall have forty-five (45) days from receiving the additional repair orders to rebut the presumption that the dealer's proposed mark-up and labor rates are reasonable.