I get it is unfeasible for you to refund everyone their actual money, or at least time consuming/unwilling to, so how about give everyone the free item they were actually expecting for this month, and THEN specify for future points how they work and stuff.

You could at least do that as some people don't want a turnip refund/they've lost out and you're still holding their funds with no gain to those users, that's incredibly unfair.