All garbage hauler licensees shall maintain one or more offices within the zoning jurisdiction of the City of Grand Island at all times during the license year, which are available for contact by the public from 8:00 a.m. to 5:00 p.m. from Monday through Friday, and from 8:00 a.m. to 12:00 Noon on Saturday. A licensee may use an automatic telephone answering machine or similar device for this requirement.