In the case where the Secretary determines that a PDP sponsor offering a prescription drug plan has violated the requirements for total reimbursement for essential retail pharmacies that are independent community pharmacies under subparagraph (C)(v)(II), the Secretary shall— (aa) if the amount of total reimbursement paid by the sponsor to an essential retail pharmacy that is an independent community pharmacy for a covered part D drug was less than the amount of total reimbursement required to be paid to the pharmacy under subparagraph (C)(v)(II) for such drug, require the PDP sponsor to pay to the pharmacy an amount equal to the difference between such amounts