It might be worthwhile to Give Snap on a call Directly, Im not saying your Dealer is Lying, as im sure you know that Special Order Items generally cant be returned/cancelled. Whether that Riser is Special Order, I have No idea. Did your New Job completely take you out of the Automotive Field? Or Entail you getting rid of the Bottom Box?
Over the Years ive bought quite a few Mechanics sets from Guys who changed crafts etc, Its Generally Not a Money making venture (for them), especially in regards to boxes/Accessories. Hopefully you can get it Canceled, Id be willing to bet your Dealer has had to deal with lots of buyers remorse over the years. Im not saying thats where your at, Changing Jobs is entirely different scenario but making that sort of investment knowing that your looking for other work is a bit reckless IMO.
Good Luck and if doesnt get resolved.. Pics Man...
BTW I logged into my Snap on Account, Clicked on the Epic Workstations and tried to add them to my Cart and none of them show stock items.