the Secretary a written complaint relating to an assessed or invoiced air traffic services charge or fee, the Secretary shall issue a final order determining whether the charge or fee is correct. (2) Not later than 30 days after such complaint is filed with the Secretary, the Secretary shall dismiss the complaint if no significant dispute exists or shall assign the matter to an administrative law judge. Thereafter, the matter shall be handled in accordance with part 302 of title 14, Code of Federal Regulations, or as modified by the Secretary, to ensure an orderly disposition of the matter within the 90-day period referred to in paragraph (1) and any specifically applicable provisions of this section. (3) The administrative law judge shall issue a recommended decision not later than 45 days after the complaint is assigned or within such shorter period as the Secretary may specify. (4) If the Secretary, upon the expiration of 90 days after the filing of the complaint, has not issued a final order, the decision of the administrative law judge shall be deemed to be the final order of the Secretary. (5) Any party to the dispute may seek review of a final order of the Secretary under this subsection in the Circuit Court of Appeals for the District of Columbia Circuit or the court of appeals in the circuit with venue. (6) Any findings of fact in a final order of the Secretary under this subsection, if supported by substantial evidence, shall be conclusive if challenged in a court pursuant to this subsection. No objection to such a final order may be considered by the court unless objection was urged before an administrative law judge or the Secretary at a proceeding under this subsection or, if not so urged, unless there were reasonable grounds for failure to do so. (e) Payment under protest