Only Congress can help.
(a) Excepted service has the meaning given that term by section 2103 of title 5, United States Code, and includes all positions in the executive branch of the Federal Government which are specifically excepted from the competitive service by or pursuant to statute, by the President, or by the Office of Personnel Management, and which are not in the Senior Executive Service.
https://www.ecfr.gov/current/title-5/chapter-I/subchapter-B/part-213
Office of Personnel Management Summary of Grades.
(1)in determining the rate of basic pay which an employee will receive—
(A) the principle of equal pay for substantially equal work will be followed; and
(B)variations in rates of basic pay paid to different employees will be in proportion to substantial differences in the difficulty, responsibility, and qualification requirements of the work performed and to the contributions of employees to efficiency and economy in the service; and
(2) individual positions will, in accordance with their duties, responsibilities, and qualification requirements, be so grouped and identified by classes and grades, as defined by section 5102 of this title, and the various classes will be so described in published standards, as provided by section 5105 of this title, that the resulting position-classification system can be used in all phases of personnel administration. (Pub. L. 89–554, Sept. 6, 1966, 80 Stat. 443.)
5 U.S. Code § 5102 – Definitions
(a) Agency and employee have the meanings given them by section 5102 of title 5, United States Code.
(b) Class means all positions which are sufficiently similar as to (1) kind or subject-matter of work, (2) level of difficulty and responsibility, and (3) the qualification requirements of the work, to warrant similar treatment in personnel and pay administration.
(c) Classification means the analysis and identification of a position and placing it in a class under the position-classification plan established by OPM under chapter 51 of title 5, United States Code.
(d) Grade means all classes of positions which (although different with respect to kind or subject-matter of work) are sufficiently equivalent as to (1) level of difficulty and responsibility, and (2) level of qualification requirements of the work, to warrant their inclusion within one range of rates of basic pay.
(e) Position means the work, consisting of the duties and responsibilities, assigned by competent authority for performance by an employee.
The purpose of 5 USC Ch. 51: CLASSIFICATION (house.gov) was to create the classification of positions whereby in determining the rate of basic pay which an employee will receive and the principle of equal pay for substantially equal work. Variations in rates of basic pay paid to different employees will be in proportion to substantial differences in the difficulty, responsibility, and qualification requirements of the work performed and to the contributions of employees to efficiency and economy in the service; and (2) individual positions will, in accordance with their duties, responsibilities, and qualification requirements, be so grouped and identified by classes and grades, as defined by section 5102 of this title, and the various classes will be so described in published standards, as provided by section 5105 of this title, that the resulting position-classification system can be used in all phases of personnel administration.
Article 23 of the Universal Declaration of Human Rights
· Everyone has the right to work, to free choice of employment, to just and favorable conditions of work and to protection against unemployment.
· Everyone, without any discrimination, has the right to equal pay for equal work.
· Everyone who works has the right to just and favorable remuneration ensuring for himself and his family an existence worthy of human dignity, and supplemented, if necessary, by other means of social protection.
· Everyone has the right to form and to join trade unions for the protection of his interests.
https://www.humanrights.com/course/lesson/articles-19-25/read-article-23.html