All franchises heretofore granted are recognized as contracts between the City of Freeport and the grantee, and the contractual rights as contained in any such franchise shall not be impaired by the provisions of this Charter. Every public utility franchise hereafter granted shall be held subject to all the terms and conditions contained in the various sections of this Article whether or not such terms are specifically mentioned in the franchise. Nothing in this Charter shall operate to limit in any way, as specifically stated, the discretion of the City Council or voters of the City in imposing terms and conditions as may be reasonable in connection with any franchise grant.