In-game kills system having wonky interactions with shop. Spend 4, get a kill, adds 5 not 1. Input?

Sorry for wonky title, hard to articulate with only 100 characters.

To preface this, I've tweaked the default Roblox leaderboard to reward 5 Kills (renamed points) for each kill. This doesn't seem to be part of the problem, but I figured I'd mention it anyways.

So I have an in-game shop that takes these kills, and you can use them to purchase items. The issue arises when a player spends money and gets another kill. Lets say I had 50 points, and then I spent 15. I now have 35 points, and when I kill another player I should get 40 points, but it instead brings me up to 55, as if I had never spent any to begin with.

Any ideas, or further details I forgot to include?

(P.S, does anyone know how to make a leaderboard give you the kill if you tagged the player and they fell off the edge? Thanks!)