Thanks guys.

On my second failed attempt I noticed the overseas billing address stuff, but after 3 cancellations I'm pretty sure that using a forwarder is the issue. I'm kinda scuppered due to needing someone else to deliver to. At the moment, I'm not really inclined to drive from the north of the GTA to Buffalo just for a few Steelbooks!

Did win an eBay auction on the 4K "Captain America: The First Avenger" Steelbook at a not too exorbitant price so maybe I'll see if I can do the same with GoTG; although I'll keep an eye on BB Can and also Zavvi.