The bugged refund system isn't causing customs to be refunded unintentionally. The bug involves refunds occurring (by player or admin) and the money not being reimbursed.
Ignatius, contact me in-game and please don't just say "hi" or "hi street" as that will not get my attention. Start off by PMing me the issue and I will fix it ASAP.
(Or just forum PM me your DeviceID, it's found in the Feedback menu in-game).