First of all, I’m really sorry you can’t find your size. I know that’s super frustrating, especially for a line as gorgeous as the Dita Von Teese Collection.
Secondly, I’m so glad you asked this because it brings up a really important point when it comes to lingerie manufacturing/retailing that most customers aren’t aware of. Namely, that what gets made depends on the orders that get placed. So, if there are no stores that place orders for G cups, then they’re not going to get made in the factories, which means they’re not going to be available for sale later…despite the fact that Dita Von Teese has the capability to make those cup sizes. In other words, it’s not always the designer’s fault when you can’t find what you want in stores. Retailers have to buy into the size range as well.
That said, I know Debenhams’s used to carry G cups from this line, though I don’t think they have any in stock now. Glamuse and Journelle carry up to F cups, so sister sizing may be an option. But other than that, I’m not seeing those fuller bust sizes from most retailers right now. If anything, they’re extending their stock into plus sizes.