Well, depending on the number of updates they issue over the next 12 months, they're going to be giving away a lot of free books. Since they claim to have lost all customer purchase records, how can they really verify your past purchase?
If we release a new version of Charles Dickens between now and 31st January 2014, you can claim a free update for that eBook with the four-digit Order no. from your previous order email (e.g. Order no. 5019). Please send an email to email@example.com with the following information:
SUBJECT: APPLICATION FOR UPDATE COUPON
MESSAGE: Charles Dickens Kindle eBook. Order no. 5019
This order number will allow us to confirm your previous order and issue you a coupon code for the Dickens eBook, which you can use at once to re-purchase the title for free.
I mean - they either have your purchase records or they don't ...
and, FWIW, not all legitimate order numbers are 4 digit - I saved my confirmation emails, and my very first order number (which contained the Charles Dickens volume cited above) was under 100.