We don't want anyone to be stuck with Notgrass if it's not working for you. We understand that our curriculum is not the best fit for every family. Here's our return policy:
http://www.notgrass.com/notgrass/terms-conditions.html
We ask you to return the books within a month or so after you start using the curriculum (not after purchase, as long as its the current edition). Even if you've started writing in the consumable books, you can get a refund, too. (Just return the cover of the consumable books and recycle the inside pages to save shipping.)
You will have to pay for return shipping. Otherwise, you'll get a full refund of your original purchase price for the books.
All the best,
John