Fictionwise is probably - in my opinion - the most understanding distributor of ebooks out there.
Even though they state publicly that once you buy a secure format, you can't return it, you should still email them and explain the situation.
Only in one instance have they ignored me, and this was for a misspelling of a book, crippling the look-up of this title (Re: "Wierd" instead of "Weird".)
But that's ok. My wife ignores me, too. Hahahahahah, that's a joke. (I just got married!)
Email them; you won't lose a postage stamp.
Don