All charges to customers made by persons licensed under this chapter for installing, servicing, maintaining or repairing receiving equipment shall be made out in duplicate form, one of which shall be delivered to the customer when completed and shall state indelibly, accurately and clearly the date or dates when the work was performed, the make, model and serial number of the receiving equipment, the full name and license number of the licensed person, the name and address of the customer, the customer complaint, and a computation of the charge. Such computation shall separately specify the work for which such charge was made and the amount charged for labor and for each part or replacement, whether such part or replacement was new or used.