For what it’s worth, Fairphone acknowledged this was a general design fault with the “regular case” long ago, and you would have gotten the newer “slim case” (introduced around October 2016) for free.
Perhaps you still could get it for free if you would ask them, but living in South America, to where Fairphone doesn’t ship, you would need a proxy address in Europe to handle shipments (if there’s no family/ friends/ acquaintances, you could ask here in the forum).
This is a community forum, not the company. Fairphone staff occasionally might read along and engage, or not.
If you say previous communications … you did contactsupport about this in the past?