I have also found at least three different invoices, two with the same invoice number (one of just the buyers premium and one for all of the charges), and then also one pdf version for just the equipment + VAT (which has a different invoice number). The instructions just tell you to use the "invoice number" as the reference, except for my bank you couldn't put the invoice number to the reference field because it contained a letter. So I ended up putting it to the text field. All in all very confusing instructions and terms for pretty much everything.