The Town Council may from time to time amend, change, modify or repeal any regulations, limitations and restrictions of this chapter, including the Zoning Map. No such amendment, change, modification or repeal shall be adopted until after a public hearing is held thereon by the Town Council at which parties in interest and citizens shall have an opportunity to be heard. In addition to the notice required by law, notices of such hearing shall be mailed to every civic association or association of residents in the Town which shall have registered its name and address for this purpose with the Town Clerk. Failure to give such notices by mail shall not, however, invalidate any such amendment, change, modification or repeal. No amendment or change shall become effective unless the ordinance proposing such amendment or change shall first have been submitted to the Planning Commission for approval or disapproval or suggestions, and the Planning Commission shall have 30 days after the formal submission of the proposed amendment or change for consideration and report. In the case of an unfavorable report by the Planning Commission, such amendment or change shall not become effective except by a favorable vote of 3/4 of the Town Council.