13.—(1) An employer shall not penalise an employee—

(a) for invoking any right of the employee to be treated, in respect of the employee's conditions of employment, in the manner provided for by this Part,

(b) for having in good faith opposed by lawful means an act which is unlawful under this Act,

(c) for giving evidence in any proceeding under this Act or for giving notice of his or her intention to do so or to do any other thing referred to in paragraph (a) or (b), or

(d) by dismissing the employee from his or her employment if the dismissal is wholly or partly for or connected with the purpose of the avoidance of a fixed-term contract being deemed to be a contract of indefinite duration under section 9(3).

(2) For the purposes of this section, an employee is penalised if he or she—

(a) is dismissed or suffers any unfavourable change in his or her conditions of employment or any unfair treatment (including selection for redundancy), or

(b) is the subject of any other action prejudicial to his or her employment.