3. The Authority may only suspend, revoke or amend the conditions for a radio-frequency spectrum licence or declare vacant any radio-frequency spectrum that has been assigned in the cases set forth in subparagraphs c), d) and e) of paragraph 2 of this article if: a) The licensee has failed to rectify the non-compliance within a reasonable time after being requested to do so by the Authority in writing; b) The relevant non-compliance has occurred repeatedly and, along with other repeated incidences of non-compliance, shows an accumulated pattern of serious disrespect for the present Decree-Law and regulatory measures issued thereunder; c) The relevant non-compliance has or is reasonably likely to have a relevant adverse effect on other service providers, consumers or competitors, or significantly hinders the Authority from performing its functions or responsibilities or exercising its powers under the present Decree-law; d) The suspension, revocation or amendment of the conditions of a radio-frequency spectrum licence or the declaration as vacant of any radio-frequency spectrum that has been assigned is proportionate to the seriousness of the non-compliance; and e) All other effective remedies have been exhausted, including any imposition of administrative penalties. 4. The Authority may, with at least two months prior written notice and without compensation, declare vacant any radio-frequency spectrum that has been assigned if the relevant radio-frequency spectrum is not used effectively or has not been committed for significant use in the foreseeable future, and there is demonstrable demand from other persons for making effective use of all or part of such radio-frequency spectrum. 5. The Authority may, with appropriate compensation, require a person to vacate radiofrequency spectrum previously assigned to such person, and assign such radio-frequency spectrum to another person or persons if necessary or expedient to further the objectives of a national radio-frequency spectrum plan or the objective provided for in article 2 of the present Decree-law. 6. The obligation to compensate the person required to vacate the radio-frequency spectrum pursuant to paragraph shall be the responsibility of the Authority which may: a) Recover such compensation from any new person or persons assigned the vacated radiofrequency spectrum; and b) Pay such compensation in the form of cash or of, upon agreement, credits against fees and levies due, the allocation of alternative radio-frequency spectrum or some other form. 7. Where a person is required by the Authority to vacate any radio-frequency spectrum that has been assigned to it, the Authority shall allow such person a reasonable period of time