OMG, what a terribly run campaign!
Surely you should have told everyone:
1) Don't buy more than 1 in the same transaction.
2) Find an actual chart return shop! Not all shops report sales data to the charts, so a good number of the purchases you guys have made were completely pointless (and could account for the discrepancy between signups and purchases).
Still, you do stand a better chance of getting to #1 from #3 than from nowhere, so either you'll get it next week or never.