[2021] How do I get a refund for the supporter's edition upgrade?

Hey guys, I pre-ordered Icarus two days before launched. I played it for an hour and didn't quite like it so now I'm asking for a refund.

However, when I do ask for one I'm only getting a refund for the base game and not for the upgrade. Am I doing something wrong? This is quite troubling because the upgrade is like twice the cost of the base game.