You know what bugs me? Well yes that too, but also this:
A company I've known for a couple of decades as: Joe Friday Company* has changed their name to: Friday Company, Joe
A customer is charged sales tax. They know that they are exempt from same, they just need to provide documentation (an exemption certificate) which they do--with their payment. Instead of deducting the tax from the payment and asking us to credit the transaction to even, they pay the tax, ask for a credit and then a refund for the overpayment.
Our order processing software does not identify billing documents as invoices. The software issues order numbers instead. I stamp every order document meant as a billing document, submitted for payment: INVOICE PLEASE REMIT Additionally, every document has a message center. The message center has the following statement: PLEASE PAY BY ORDER NUMBER / INVOICE. REMIT "BALANCE". Customers call to say they can't find the invoice number on order number 123456A.
Save a heart attack Ain't nobody humping around Happy Wednesday.
*an example for illustrative purposes only.