17.—(1) Having determined the costs payable to a representative in accordance with these Regulations, the appropriate officer shall notify the representative of the costs payable and authorise payment accordingly.
(2) Where the costs payable under paragraph (1) are varied as a result of any redetermination or appeal made or brought pursuant to these Regulations—
(a)where the costs are increased, the appropriate officer shall authorise payment of the increase;
(b)where the costs are decreased, the representative shall repay the amount of such decrease; and
(c)where the payment of any costs of the representative is ordered under regulation 20(14) or 21(8), the appropriate officer shall authorise payment.