The grantee of a franchise may not sell, assign, sublet, or allow another to use the same, unless the Council gives its consent. Nothing in this section shall limit the right of the grantee to mortgage the grantee’s property or franchise, nor shall it restrict the rights of the purchaser, upon foreclosure sale, to operate the same; but such mortgagee or purchaser shall be subject to the terms of the franchise, the provisions of this Charter, and the ordinances of the City.