You mentioned you know how to code. Have you seen anything like this before?

Well it seems like a problem with your cart, may come from my browser I dont know it looks mor elike an internal thing.

When you try yourself are you logged in as admin ?

I have had this kind of thing related to CMSs allowing admins to do anything on the site and normal users not...

BTW the download link was expired...
Im going to try using opera browser and the code