When auditing Accounts Receivable for company A, which had a balance of $100,000,000 on December 31, 2018, the auditor send out 10 confirmations to customers, totaling $80,000,000 of the balance. 7 of these confirmations are returned that state the customer agrees with the balance. The other 3 confirmations, which total $10,500,000, were not returned. These 3 customers have yet to pay any amounts in 2019. The auditor asked for the invoices and sales contracts related to these three receivables and the company cannot locate this document. As an auditor what should you write in your report regarding this situation and what rule of accounting is this situation violating? Or what do you, as an auditor, think of this situation? Does this situation relate to accounting valuation?