I've just found an interesting quirk. Abandoned shopping carts. Now, they say that 80% of all shopping carts online are left before completing, so that part doesn't surprise me really - it's the combination of these and frustrated adgrunts who can't figure out why they haven't gotten their upgrade that stump me. You need to complete the process to get the upgrade, mate. ;)
If you ran into any technical difficulties when trying to upgrade, email hostmaster AT ad-rag.com what happened asap and we'll do everything we can to help.
Ok, so an adgrunt wanders into the product page, picks his poison and adds it to their cart. Presto, a cart appears in the top left reflecting their choice.

After this all you need to do is choose between plastic or brownie points and checkout. Some don't do this for whatever reason, maybe they simply changed their mind.