If you provide a service, document that the service was successfully provided.
For example, create a work order for your customer to review and sign for your records.
A receipt is documentation that payment has been made to finalize a sale. It serves as proof of ownership in most cases. It lists goods or services, prices, credits, discount, taxes, total amount paid and method of payment. Receipts generally include information about buyers and sellers, in different formats and to varying degrees.
Proof of service differs from a receipt because they are written requests from buyers to sellers authorizing the shipment or delivery of goods with agreement to pay.
For more information on best practices when accepting cards please go here.