Hi Gabriel,
Some quick questions so that we can figure out what's going on
What platform are you trying it on - Android, IOS, PC?
What market do you buy from - Play, Amazon, ITunes, Desura, Steam?
Have you been able to buy the extra characters?
And finally - are you able to provide screenshots of the two screens you can see?
For Android, what I understand is:
From the main menu, I would click on "Store"
You would see Episode 1: Death's Consort
There should be a price and you should also see a purchase button of some sort.
When you buy it, the price should change to "Purchased" and you should no longer be able to select that item in the game store.