Cross-referencing Two Spreadsheets

Basically I order thrice a week from a certain supplier to fill the shelves of my shop.

They make available to me two spreadsheet dumps: an orders spreadsheet, with the following columns:-

order ref
date
unique product code
description
qty

9262
03/07/2013
622642
Fabric Dye
4

And an invoices spreadsheet with the following columns:-

invoice ref
date
unique product code
description
qty

122551
04/07/2013
622642
Fabric Dye
4

Basically I can see the potential here to find out what we've ordered but that which they haven't sent which would be so handy.

I have tried to vlookup() produce code against product code, this kind of works but below are some example drawbacks:-

1) no idea if I've ordered it ten times and they've only not sent it once, or if I've ordered it ten times and they've not sent it nine times.
2) no idea of dates - i.e. ordered this in June '13, October '13 and February '14 and they sent it in February '14 only.