I know the original MasterScreen sold out, and rumor has it there's a new 4-panel version shipping from the manufacturer to Citizen on Monday. I'll bet you'll be taken care of soon.
Meanwhile, I think you've had the misfortune of trying to communicate with a company dealing with a state of flux (things I'm aware of having an impact on them include the implosion of Wizard's Attic, a cross-country move, the GAMA Trade Show, and a lot more).
I think a lot of publishers try and offer mail order as a service to their customers, knowing that local game stores can't or won't always stock the products. This trips them up sometimes, though, because they're not really built around being retailers, and don't have the staff to devote to customer service, following up on lost shipments, etc. Doing all those things directly detracts from their core mission.
In fact, we at Atlas Games got out of mail order completely for this very reason. We now outsource all our mail order to Warehouse 23 -- our website points people to their shopping cart when they need to buy stuff online (because, we presume, they can't find it locally; W23 doesn't discount and does charge shipping, so there's no price advantage to buying online). We want to have a back-up channel to get the games to people, but frankly I think doing our own mail order represented a net loss for us, when you add up the cost of the staff time it ate up (doing it, dealing with the problems that arose, answering the customer service queries, figuring out shipping estimates to the far corners of the globe--only to see people say, "Oh, air mail to Myanmar costs that much? never mind!" etc.), and the opportunity cost of what better things we might do with our time, even though we got full retail from the items we sold. Sure, I might have made $20 on a sale, but making that sale and giving the customer prompt service might have delayed a book from going to press on time, or might have been time that could have been better spent persuading a book chain buyer to pick up hundreds of copies of the same book.
And NOT giving prompt service because you're trying to focus on the big picture of the company's priorities...generates customer service complaints on the web.