(a) Records. All work done by a registrant or any employee thereof shall be recorded on an invoice in such detail as is required by rule or regulation of the county executive and shall describe all service work done and all parts supplied. If any used parts are supplied, the invoice shall clearly state that fact. One (1) copy shall be given to the consumer and one (1) copy shall be retained by the registrant for a period of at least one (1) year.
(b) Estimates. All consumers shall have the right to request a written estimate for labor and parts necessary for a specific job. If a written estimate is requested, a registrant shall make such an estimate, specifying the nature of the repair or maintenance required, the charges for specific parts and the charges for labor. Final charges may not exceed estimates by more than ten (10) percent without the consent of the consumer. Registrants may make a reasonable charge for giving an estimate. However, such charge shall be disclosed, in writing, to the consumer prior to acceptance by the registrant of the request for an estimate.
(c) Returned parts. Upon request, registrants shall return to a requesting consumer any part which such registrant has replaced, unless such parts are required by warranty to be returned to the manufacturer.
(d) Posting of notices. All business establishments which engage in the installation, maintenance and repair of radio and television equipment and electrical appliances shall post in a conspicuous place at the place of business a sign to be furnished by the county stating: "Under the provisions of the Montgomery County Code, all customers are entitled upon request to receive a written estimate, for which a fee may be charged, before repair work is begun. Customers are also entitled upon request to the return of replaced parts except those under warrant." (1975 L.M.C., ch. 5, § 1.)