There's no purchase order, or invoice you can get off the cosco.com website, to print off? I've never ordered from them, but other sites let you log into your account and view past orders/invoices. What about a copy of the UPC, from the system's box? I don't know if they'd except that either, but you could probably find out.How am I suppose to submit a proof from Cosco.com if they didn't send an invoice? They didn't except my email reciept.