Math trade wrong edition arrived — how mad is fair

Did a BGG math trade — first time — felt like a genius for optimizing wants like a human algorithm.

Package shows up and it’s the wrong printing: missing a small expansion module that was literally why I wanted the trade. Box art slightly different, component count off, my heart on fire.

Trader says ‘oh I thought that was included in all copies’ and I’m stuck being the picky guy who cares about cardboard modules.

What’s normal resolution here? Split shipping on a return? Partial refund? Accept fate and buy the module separately like a chump?

Trying not to torch someone’s trade reputation over an honest mistake, but also I traded away a game I liked for a reason.

If you’ve mediated a trade gone weird, how did you keep it civil?