Notwithstanding any other section of this chapter and except as provided in subsection (b), any cotton producer against whose cotton any assessment is made and collected from him under the authority of this chapter and who is not in favor of supporting the research and promotion program as provided for herein shall have the right to demand and receive from the Cotton Board a refund of such assessment: Provided, That such demand shall be made personally by such producer in accordance with regulations and on a form and within a time period prescribed by the Board and approved by the Secretary, but in no event less than ninety days, and upon submission of proof satisfactory to the Board that the producer paid the assessment for which refund is sought, and any such refund shall be made within sixty days after demand therefor.