Ask HN: Debt rising on DigitalOcean

Using Github student pack I got $50 free credit on Digital Ocean. After 10 months I deleted my droplet. Even though it was billed $5 monthly, at the end I saw that I owe $0.04. I forgot about it for a while, logged in today and saw that I owe $0.15. Minimal transfer from PayPal is $5. How to solve this?