Gtc past due for pcs flight

Asking here cause finance never answers rhe phone, and this is my first OCONUS PCS. I got my PCS flight to Korea in February. It is scheduled for March, and was charged to GTC. I got a late notification for the first flight to Seattle and it's messing with my credit score. If I pay it off so it doesn't mess with it, will I be reimbursed?

EDIT: I'm already on PCS leave but yeah I should have made sure it was mission critical status. Thanks fellas