Was recently laid off and am now being asked to pay the company

I was just recently laid off, and I am now being asked to pay for time that I over spent through my Vacation benefits. I was never walked through these procedures, I was never given any paper work and explained how Vacation time worked, and when ever I would log on to the companies employee section to check on vacation time, it would show total hours "EARNED" not borrowed. What can I legally do? I have 30 days to dispute this. Any help would be great. If you need a copy of the letter given to me, I would be more than happy to PM it