Every Leanpub customer has a Library where they can read the books and take the courses that they've purchased.
You can also get a refund for a book right from the library.
So, if you buy a Leanpub book and then discover it's part of a larger bundle that you want, the best thing to do right now is this:
Go to your Library
Click the book
Click the "Request Refund" button
Go buy the bundle which contains the books that you want.
Note that you have 60 days to get a refund on a book purchase, so there's no rush. We're a bootstrapped startup, and we greatly appreciate your business.
Thanks for being a Leanpub customer!
P.S. Eventually we'll have a better solution to this than using the refund mechanism. When we do, we'll update this article. But for now, this is the best thing to do...