Negative Balance in goSFU

hi everyone! i was just wondering what it means if my gosfu account inquiry balance is negative? long story short, i paid my tuition on the day tuition was due, and when my student loans were released, SFU took money from my student loans even though i already paid from my bank a few days prior. i requested a refund, but i don't think i've received it yet, but i have a negative balance on my goSFU account. anyone able to help me out? thank you :)