If you're really registered, then just ask the school for a confirmation. If they confirm you are, then simply enjoy the cooking class, with or without a DTV linked to it.
I already got mine, in 3 business days. Through an agent who tries for you until you're approved, or refunds you. Stop talking like you 'know everything'.
some agents offer refunds if you are rejected. And for a cheap price. They just have lots of customers, which compensate for any loss. That's what makes them an interesting option if you don't want to deal with it yourself.
Just make sure your agent 'guarantees' you the visa approval (or money back). My agent got my DTV very quickly, for a low fee, and it was totally stress-free. I could probably have done it myself, but why bother when these guys ensure everything is perfectly done so that you get approved? When I see so many people here getting their application cancelled or rejected, I'm glad I didn't do it myself. For a few thousand baht, it's worth it. For more than that, I'd probably reconsider.