If you contact either a professional joiner or carpenter you should be pointed in the right direction.

The first thing you should do is ask your friends to recommend you a carpenter if you can. Even specific companies that produce bunk beds are unlikely to stock an item such as this rare that they are. If money isn't a problem, and there's a decent manny it isn't considering how expensive these units are, than getting one custom made is definitely an option. I think the first thing you must know about twin over queen bunk beds is how rare they are to find as well as purchase.

I'd personally recommend a carpenter because they're far better managing wood where detail is involved. If you want to buy this kind of an item it's the kind of thing you need to buy online or that you need to research. Simple Googling the phrase won't help because it's unlikely that anyone will be making what you want unless you're in a very big city.

If you are looking to buy this type of bunk bed then I'll tell you right away that your normal bed retails aren't going to cut it.