No amendment or extension of any franchise, right, lease or privilege that now exists, or that may hereafter be authorized, which extends or enlarges the time or territory of such franchise, right, lease or privilege, shall be granted by any city or town until the provisions of §§ 15.2-2101 through 15.2-2104 have been complied with. No amendment that releases the grantee, or his assignee, from the performance of any duty required by the ordinance or that authorizes an increase in the user charges to be made by such grantee or assignee shall be granted until notice of such proposed amendment has been given to the public by advertising the proposed amendment for seven days in some newspaper having general circulation in the city or town. The cost of such advertising shall be paid by the city or town, which shall be reimbursed by the person to whom the amendment is granted. No such amendment shall be adopted except by ordinance.