(1) A dissenting stockholder may not withdraw his demand for payment of the fair value of his shares without the written consent of the participating bank.
(2) The enforcement by a dissenting stockholder of his right to receive payment for his shares shall exclude the enforcement by such dissenting stockholder of any other right to which he might otherwise be entitled by virtue of share ownership, except as provided in subsection (2) of section 8 and except that this subsection shall not exclude the right of such dissenting stockholder to bring or maintain an appropriate action to obtain relief on the ground that consummation of the plan of acquisition will be or is ultra vires, unlawful or fraudulent as to such dissenting stockholder.