How long until unpaid charges become loans

Currently have around 3.6K in unpaid charges and I got an email recently with the urgent tagline saying I needed to pay it off before it became a hold. No way we can pay this without taking out another loan, so I'm wondering what to do. Also it was peculiar since it stated that I have charges every semester dating back to fall 2024 even though I already took out loans for those previous time periods...