Ebay will have sent an invoice at the time of sale.
There is no requirement for sellers to send invoices and private sellers would not have the facility to do so, relying only on the Ebay invoice.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)