How to take legal action against a college?

I enrolled in INIFD for interior design last year, joining in the second semester of my first year. Due to financial difficulties, I'm unable to pay the fees for my second year, and as a result, I've decided to drop out. However, when I informed the college about my decision, they insisted that I pay the first-year fees as well, which was not communicated to me during admission. They are threatening legal action if I don't comply, even though I never signed any document mentioning these rules.